question_answer 1)
Radioactive substance do not emit [CPMT 1997; AIEEE 2003]
A)
Electron done
clear
B)
Helium nucleus done
clear
C)
Positron done
clear
D)
Proton done
clear
View Solution play_arrow
question_answer 2)
In a radioactive substance at \[t=0\], the number of atoms is \[8\times {{10}^{4}}\]. Its half life period is 3 years. The number of atoms \[1\times {{10}^{4}}\] will remain after interval [MP PMT/PET 1988]
A)
9 years done
clear
B)
8 years done
clear
C)
6 years done
clear
D)
24 years done
clear
View Solution play_arrow
question_answer 3)
The half-life period of radium is 1600 years. The fraction of a sample of radium that would remain after 6400 years is [NCERT 1980; SCRA 1994; JIPMER 1997 CBSE PMT 1994; MNR 1998; MP PMT 2004; DPMT 2004]
A)
\[\frac{1}{4}\] done
clear
B)
\[\frac{1}{2}\] done
clear
C)
\[\frac{1}{8}\] done
clear
D)
\[\frac{1}{16}\] done
clear
View Solution play_arrow
question_answer 4)
During a negative beta decay [IIT 1987; MNR 1990]
A)
An atomic electron is ejected done
clear
B)
An electron which is already present within the nucleus is ejected done
clear
C)
A neutron in the nucleus decays emitting an electron done
clear
D)
A part of the binding energy is converted into electron done
clear
View Solution play_arrow
question_answer 5)
Some radioactive nucleus may emit [IIT 1986]
A)
Only one \[-13.6\ eV\] or \[\gamma \]at a time done
clear
B)
All the three \[_{92}{{U}^{238}}\] and \[\gamma \] one after another done
clear
C)
All the three \[\alpha ,\ \beta \] and \[\gamma \] simultaneously done
clear
D)
Only\[\alpha \] and \[\beta \] simultaneously done
clear
View Solution play_arrow
question_answer 6)
Which can pass through 20 cm thickness of the steel [MNR 1985; CPMT 1990; RPET 2000]
A)
\[\alpha -\]particles done
clear
B)
\[\beta -\]particles done
clear
C)
\[\gamma -\]rays done
clear
D)
Ultraviolet rays done
clear
View Solution play_arrow
question_answer 7)
The half-life period of radium is 1600 years. Its average life time will be [MP PET/PMT 1988]
A)
3200 years done
clear
B)
4800 years done
clear
C)
2319 years done
clear
D)
4217 years done
clear
View Solution play_arrow
question_answer 8)
What percentage of original radioactive atoms is left after five half lives [AFMC 1996; RPMT 1996]
A)
0.3% done
clear
B)
1% done
clear
C)
31% done
clear
D)
3.125% done
clear
View Solution play_arrow
question_answer 9)
Beta rays emitted by a radioactive material are [IIT 1983; ISM Dhanbad 1994; AFMC 1997; BHU 2000; AIEEE 2002]
A)
Electromagnetic radiation done
clear
B)
The electrons orbiting around the nucleus done
clear
C)
Charged particles emitted by nucleus done
clear
D)
Neutral particles done
clear
View Solution play_arrow
question_answer 10)
Alpha rays emitted from a radioactive substance are [CBSE PMT 1999; RPET 2000]
A)
Negatively charged particles done
clear
B)
Ionised hydrogen nuclei done
clear
C)
Doubly ionised helium atom done
clear
D)
Uncharged particles having the mass equal to proton done
clear
View Solution play_arrow
question_answer 11)
In the given reaction\[_{z}{{X}^{A}}{{\to }_{z+1}}{{Y}^{A}}{{\to }_{z-1}}{{K}^{A-4}}{{\to }_{z-1}}{{K}^{A-4}}\]Radioactive radiations are emitted in the sequence [AIIMS 1982; CBSE PMT 1993; AFMC 1999; MP PET 2002]
A)
\[\frac{2{{\varepsilon }_{0}}hc}{{{e}^{2}}}\] done
clear
B)
\[\beta ,\ \alpha ,\ \gamma \] done
clear
C)
\[\gamma ,\ \alpha ,\ \beta \] done
clear
D)
\[\beta ,\ \gamma ,\ \alpha \] done
clear
View Solution play_arrow
question_answer 12)
Half-life of \[B{{i}^{210}}\] is 5 days. If we start with 50,000 atoms of this isotope, the number of atoms left over after 10 days is [MP PET 1993]
A)
5,000 done
clear
B)
25,000 done
clear
C)
12,500 done
clear
D)
20,000 done
clear
View Solution play_arrow
question_answer 13)
A nucleus of atomic mass A and atomic number Z emits \[{{M}_{1}}\]particles. The atomic mass and atomic number of the resulting nucleus are [CPMT 1982]
A)
A, Z done
clear
B)
A + 1, Z done
clear
C)
A, Z + 1 done
clear
D)
\[A-4,\ Z-2\] done
clear
View Solution play_arrow
question_answer 14)
The radioactivity of a certain radioactive element drops to 1/64 of its initial value in 30 seconds. Its half-life is [CPMT 1990, 97]
A)
2 seconds done
clear
B)
4 seconds done
clear
C)
5 seconds done
clear
D)
6 seconds done
clear
View Solution play_arrow
question_answer 15)
Radioactivity was discovered by
A)
Becquerel done
clear
B)
Pierre Curie done
clear
C)
Roentgen done
clear
D)
Rutherford done
clear
View Solution play_arrow
question_answer 16)
The decay constant \[\lambda \] of the radioactive sample is the probability of decay of an atom in unit time, then [CBSE PMT 1990]
A)
\[\lambda \] decreases as atoms become older done
clear
B)
\[\lambda \] increases as the age of atoms increases done
clear
C)
\[\lambda \] is independent of the age done
clear
D)
Behaviour of \[\lambda \] with time depends on the nature of the activity done
clear
View Solution play_arrow
question_answer 17)
The average life T and the decay constant \[\lambda \] of a radioactive nucleus are related as [CPMT 1983]
A)
\[T\lambda =1\] done
clear
B)
\[T=\frac{0.693}{\lambda }\] done
clear
C)
\[\frac{T}{\lambda }=1\] done
clear
D)
\[{{\lambda }_{1}},\ {{\lambda }_{2}},\ {{\lambda }_{3}}\] done
clear
View Solution play_arrow
question_answer 18)
If T is the half-life of a radioactive material, then the fraction that would remain after a time \[\frac{T}{2}\] is [MP PMT 1992]
A)
\[\frac{1}{2}\] done
clear
B)
\[\frac{3}{4}\] done
clear
C)
\[\frac{1}{\sqrt{2}}\] done
clear
D)
\[\frac{\sqrt{2}-1}{\sqrt{2}}\] done
clear
View Solution play_arrow
question_answer 19)
If the decay or disintegration constant of a radioactive substance is\[\beta \], then its half life and mean life are respectively [IIT 1989; MNR 1990; MP PET 1995, 97, 99, 2002; MP PMT 1999, 2002; UPSEAT 2002]
A)
\[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] and \[\frac{{{\log }_{e}}2}{\lambda }\] done
clear
B)
\[\frac{{{\log }_{e}}2}{\lambda }\]and \[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] done
clear
C)
\[\lambda \ {{\log }_{e}}2\]and\[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] done
clear
D)
\[\begin{matrix} \lambda \\ {{\log }_{e}}2 \\ \end{matrix}\] and \[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] (loge 2 can be written as ln 2) done
clear
View Solution play_arrow
question_answer 20)
Which of the following is in the increasing order for penetrating power [IIT 1994; RPET 2003]
A)
\[\alpha ,\ \beta ,\ \gamma \] done
clear
B)
\[\beta ,\ \alpha ,\ \gamma \] done
clear
C)
\[\gamma ,\ \alpha ,\ \beta \] done
clear
D)
\[\gamma ,\ \beta ,\ \alpha \] done
clear
View Solution play_arrow
question_answer 21)
The half-life of a radioactive element which has only \[\frac{1}{32}\] of its original mass left after a lapse of 60 days is [MP PET 1992; DPMT 2002]
A)
12 days done
clear
B)
32 days done
clear
C)
60 days done
clear
D)
64 days done
clear
View Solution play_arrow
question_answer 22)
The half-life of \[B{{i}^{210}}\]is 5 days. What time is taken by (7/8)th part of the sample to decay [MNR 1986; Pb. PMT 2001]
A)
3.4 days done
clear
B)
10 days done
clear
C)
15 days done
clear
D)
20 days done
clear
View Solution play_arrow
question_answer 23)
A radioactive nucleus undergoes a series of decay according to the scheme \[A\xrightarrow{\alpha }{{A}_{1}}\xrightarrow{\beta }{{A}_{2}}\xrightarrow{\alpha }{{A}_{3}}\xrightarrow{\gamma }{{A}_{4}}\] If the mass number and atomic number of A are 180 and 72 respectively, then what are these number for A4 [Roorkee 1986; MP PET 2002; KCET 2003; DPMT 2005]
A)
172 and 69 done
clear
B)
174 and 70 done
clear
C)
176 and 69 done
clear
D)
176 and 70 done
clear
View Solution play_arrow
question_answer 24)
Radioactivity is
A)
Irreversible process done
clear
B)
Self disintegration process done
clear
C)
Spontaneous process done
clear
D)
All of the above done
clear
View Solution play_arrow
question_answer 25)
Half-life of radioactive element depends upon [NCERT 1978; AFMC 1996]
A)
Amount of element present done
clear
B)
Temperature done
clear
C)
Pressure done
clear
D)
Nature of element done
clear
View Solution play_arrow
question_answer 26)
The decay constant of radium is \[4.28\times {{10}^{-4}}\]per year. Its half life will be [MNR 1990]
A)
2000 years done
clear
B)
1240 years done
clear
C)
63 years done
clear
D)
1620 years done
clear
View Solution play_arrow
question_answer 27)
Which of the following is not a mode of radioactive decay [NCERT 1978]
A)
Positron emission done
clear
B)
Electron capture done
clear
C)
Fusion done
clear
D)
Alpha decay done
clear
View Solution play_arrow
question_answer 28)
Atomic mass number of an element thorium is 232 and its atomic number is 90. The end product of this radioactive element is an isotope of lead (atomic mass 208 and atomic number 82). The number of alpha and beta particles emitted is [CPMT 1985; Pb. PET 2003]
A)
\[\alpha =3,\ \beta =3\] done
clear
B)
\[\alpha =6,\ \beta =4\] done
clear
C)
\[\alpha =6,\ \beta =0\] done
clear
D)
\[\alpha =4,\ \beta =6\] done
clear
View Solution play_arrow
question_answer 29)
A sample contains 16 gm of a radioactive material, the half life of which is two days. After 32 days, the amount of radioactive material left in the sample is [NCERT 1984; MNR 1995; MP PMT 1995]
A)
Less than 1 mg done
clear
B)
\[\frac{1}{4}gm\] done
clear
C)
\[\frac{1}{2}gm\] done
clear
D)
1 gm done
clear
View Solution play_arrow
question_answer 30)
A radio-isotope has a half- life of 5 years. The fraction of the atoms of this material that would decay in 15 years will be [NCERT 1984; MP PMT 1996; MP PET 1997]
A)
1/8 done
clear
B)
2/3 done
clear
C)
7/8 done
clear
D)
5/8 done
clear
View Solution play_arrow
question_answer 31)
Curie is a unit of
A)
Length done
clear
B)
It is not any unit done
clear
C)
Activity done
clear
D)
Atomic number done
clear
View Solution play_arrow
question_answer 32)
Three \[\alpha -\]particles and one \[\beta -\]particle decaying takes place in series from an isotope \[_{88}R{{a}^{238}}\]. Finally the isotope obtained will be [CPMT 1989; DCE 2000]
A)
\[_{84}{{X}^{220}}\] done
clear
B)
\[_{86}{{X}^{222}}\] done
clear
C)
\[_{83}{{X}^{224}}\] done
clear
D)
\[_{83}{{X}^{215}}\] done
clear
View Solution play_arrow
question_answer 33)
Half-life of a radioactive substance is T. The time taken for all the nuclei to disintegrate will be
A)
2T done
clear
B)
T2 done
clear
C)
4T done
clear
D)
Uncertain done
clear
View Solution play_arrow
question_answer 34)
The half-life of polonium is 140 days. After how many days, 16 gm polonium will be reduced to 1 gm (or 15g will decay) [CPMT 1997; Pb. PET 2002; BHU 2004]
A)
700 days done
clear
B)
280 days done
clear
C)
560 days done
clear
D)
420 days done
clear
View Solution play_arrow
question_answer 35)
An archaeologist analyses the wood in a prehistoric structure and finds that \[{{C}^{14}}\](Half-life = 5700 years) to \[{{C}^{12}}\]is only one- fourth of that found in the cells buried plants. The age of the wood is about [NCERT 1982]
A)
5700 years done
clear
B)
2850 years done
clear
C)
11,400 years done
clear
D)
22,800 years done
clear
View Solution play_arrow
question_answer 36)
The correct order of ionizing capacity of \[a,\ \beta \]and \[\gamma -\]rays is [CBSE PMT 2000]
A)
\[\alpha >\gamma >\beta \] done
clear
B)
\[\alpha >\beta >\gamma \] done
clear
C)
\[\alpha <\beta <\gamma \] done
clear
D)
\[\alpha >\beta >\gamma \] done
clear
View Solution play_arrow
question_answer 37)
A radioactive element emits 200 particles per second. After three hours 25 particles per second are emitted. The half-life period of element will be
A)
50 minutes done
clear
B)
60 minutes done
clear
C)
70 minutes done
clear
D)
80 minutes done
clear
View Solution play_arrow
question_answer 38)
The decay constant of a radioactive element is 0.01 per second. Its half-life period is [DPMT 2001]
A)
693 sec done
clear
B)
6.93 sec done
clear
C)
0.693 sec done
clear
D)
69.3 sec done
clear
View Solution play_arrow
question_answer 39)
Consider a radioactive material of half-life 1.0 minute. If one of the nuclei decays now, the next one will decay [MNR 1994]
A)
After 1 minute done
clear
B)
After \[\frac{1}{{{\log }_{e}}2}\] minute done
clear
C)
After \[\frac{1}{N}\]minute, where N is the number of nuclei present at that moment done
clear
D)
After any time done
clear
View Solution play_arrow
question_answer 40)
The half-life of the isotope \[_{11}N{{a}^{24}}\]is 15 hrs. How much time does it take for \[\frac{7}{8}th\] of a sample of this isotope to decay [MP PET 1994]
A)
75 hrs done
clear
B)
65 hrs done
clear
C)
55 hrs done
clear
D)
45 hrs done
clear
View Solution play_arrow
question_answer 41)
If the half-life of a radioactive sample is 10 hours, its mean life is [MP PET 1994]
A)
14.4 hours done
clear
B)
7.2 hours done
clear
C)
20 hours done
clear
D)
6.93 hours done
clear
View Solution play_arrow
question_answer 42)
If 20 gm of a radioactive substance due to radioactive decay reduces to 10 gm in 4 minutes, then in what time 80 gm of the same substance will reduce to 10 gm [MP PMT 1994]
A)
In 8 minutes done
clear
B)
In 12 minutes done
clear
C)
In 16 minutes done
clear
D)
In 20 minutes done
clear
View Solution play_arrow
question_answer 43)
16 gm sample of a radioactive element is taken from Bombay to Delhi in 2 hour and it was found that 1 gm of the element remained (undisintegrated). Half life of the element is [MP PMT 1994]
A)
2 hour done
clear
B)
1 hour done
clear
C)
\[\frac{1}{2}hour\] done
clear
D)
\[\frac{1}{4}hour\] done
clear
View Solution play_arrow
question_answer 44)
Unit of radioactivity is Rutherford. Its value is [MP PMT 1994]
A)
\[3.7\times {{10}^{10}}\]disi tegrations/sec done
clear
B)
\[3.7\times {{10}^{6}}\]disintegrations/sec done
clear
C)
\[1.0\times {{10}^{10}}\] disintegrations/sec done
clear
D)
\[1.0\times {{10}^{6}}\] disintegrations/sec done
clear
View Solution play_arrow
question_answer 45)
In which radioactive disintegration, neutron dissociates into proton and electron [AFMC 1995]
A)
\[H{{e}^{++}}\] emission done
clear
B)
\[\beta -\]emission done
clear
C)
\[\gamma -\]emission done
clear
D)
Positron emission done
clear
View Solution play_arrow
question_answer 46)
The count rate of a Geiger- Muller counter for the radiation of a radioactive material of half life of 30 minutes decreases to 5\[{{s}^{-1}}\]after 2 hours. The initial count rate was [CBSE PMT 1995]
A)
25\[{{s}^{-1}}\] done
clear
B)
80\[{{s}^{-1}}\] done
clear
C)
625\[{{s}^{-1}}\] done
clear
D)
20\[{{s}^{-1}}\] done
clear
View Solution play_arrow
question_answer 47)
What is the respective number of \[\alpha \]and \[\beta \] particles emitted in the following radioactive decay \[_{90}{{X}^{200}}{{\to }_{80}}{{Y}^{168}}\] [CBSE PMT 1995; Pb. PMT 2004]
A)
6 and 8 done
clear
B)
8 and 8 done
clear
C)
6 and 6 done
clear
D)
8 and 6 done
clear
View Solution play_arrow
question_answer 48)
A radioactive reaction is\[_{92}{{U}^{238}}{{\to }_{82}}P{{b}^{206}}\]. How many \[\alpha \]and \[\beta \]particles are emitted [BHU 1995; CET 1998; RPET 1996; BHU 2000; AMU (Engg.) 2000]
A)
\[10\alpha ,\ 6\beta \] done
clear
B)
4 protons, 8 neutrons done
clear
C)
6 electrons, 8 protons done
clear
D)
\[6\beta ,\ 8\alpha \] done
clear
View Solution play_arrow
question_answer 49)
A radioactive substance has a half-life of 60 minutes. After 3 hours, the fraction of atom that have decayed would be [BHU 1995; 2000]
A)
12.5% done
clear
B)
87.5% done
clear
C)
8.5% done
clear
D)
25.1% done
clear
View Solution play_arrow
question_answer 50)
A element used for radioactive carbon dating for more than 5600 years is [BHU 1995]
A)
\[C-14\] done
clear
B)
\[U-234\] done
clear
C)
\[U-238\] done
clear
D)
\[Po-94\] done
clear
View Solution play_arrow
question_answer 51)
After two hours, one- sixteenth of the starting amount of a certain radioactive isotope remained undecayed. The half-life of the isotope is [Bihar MEE 1995; Manipal MEE 1995; EAMCET 1994 MP PMT 1997; DPMT 2002; AFMC 2000, 05]
A)
15 minutes done
clear
B)
30 minutes done
clear
C)
45 minutes done
clear
D)
1 hour done
clear
View Solution play_arrow
question_answer 52)
N atoms of a radioactive element emit n alpha particles per second. The half life of the element is [MP PET 1995; MP PMT 1997, 2003]
A)
\[\frac{n}{N}\]sec done
clear
B)
\[\frac{N}{n}\] sec done
clear
C)
\[\frac{0.693\ N}{n}\] sec done
clear
D)
\[5,099\ c{{m}^{-1}}\] sec done
clear
View Solution play_arrow
question_answer 53)
A radioactive nucleus \[_{92}{{X}^{235}}\]decays to \[_{91}{{Y}^{231}}\]. Which of the following particles are emitted [MP PMT 1995]
A)
One alpha and one electron done
clear
B)
Two deuterons and one positron done
clear
C)
One alpha and one proton done
clear
D)
One proton and four neutrons done
clear
View Solution play_arrow
question_answer 54)
The radioactive nucleus \[_{7}{{N}^{13}}\]decays to \[_{6}{{C}^{13}}\] through the emission of [MP PET 1996]
A)
Neutron done
clear
B)
Proton done
clear
C)
Electron done
clear
D)
Positron done
clear
View Solution play_arrow
question_answer 55)
The counting rate observed from a radioactive source at t=0 second was 1600 counts per second and at t=8 seconds it was 100 counts per second. The counting rate observed, as counts per second at t=6 seconds, will be [MP PET 1996; UPSEAT 2000; Pb. PET 2004; Kerala PET 2005]
A)
400 done
clear
B)
300 done
clear
C)
200 done
clear
D)
150 done
clear
View Solution play_arrow
question_answer 56)
The radioactive decay of uranium into thorium is expressed by the equation\[_{92}^{238}U\to _{90}^{234}Th+X,\]where \['X'\]is [MP PMT 1996, 2002; AMU (Engg.) 2000]
A)
An electron done
clear
B)
A proton done
clear
C)
A deuteron done
clear
D)
An alpha particle done
clear
View Solution play_arrow
question_answer 57)
The relationship between \[\lambda \]and half life \[({{T}_{1/2}})\]of a radioactive substance is [RPMT 1996; MP PMT 1996]
A)
\[\lambda =\frac{{{\log }_{10}}2}{{{T}_{1/2}}}\] done
clear
B)
\[\lambda =\frac{{{\log }_{e}}2}{{{T}_{1/2}}}\] done
clear
C)
\[\lambda =\frac{{{\log }_{2}}10}{{{T}_{1/2}}}\] done
clear
D)
\[\lambda =\frac{{{\log }_{2}}e}{{{T}_{1/2}}}\] done
clear
View Solution play_arrow
question_answer 58)
In a radioactive decay, neither the atomic number nor the mass number changes. Which of the following would be emitted in the decay process [MP PET 1997]
A)
Proton done
clear
B)
Neutron done
clear
C)
Electron done
clear
D)
Photon done
clear
View Solution play_arrow
question_answer 59)
The rate of disintegration of fixed quantity of a radioactive element can be increased by [MP PMT 1997, 2003]
A)
Increasing the temperature done
clear
B)
Increasing the pressure done
clear
C)
Chemical reaction done
clear
D)
It is not possible done
clear
View Solution play_arrow
question_answer 60)
The half-life (T) and the disintegration constant \[(\lambda )\]of a radioactive substance are related as [MP PMT/PET 1998]
A)
\[\lambda T=1\] done
clear
B)
\[\lambda T=0.693\] done
clear
C)
\[\frac{T}{\lambda }=0.693\] done
clear
D)
\[\frac{\lambda }{T}=0.693\] done
clear
View Solution play_arrow
question_answer 61)
The half-life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be [MP PMT/PET 1998]
A)
93.75% done
clear
B)
75% done
clear
C)
25% done
clear
D)
6.25% done
clear
View Solution play_arrow
question_answer 62)
Radon (Ra) decays into Polonium (\[{{P}_{0}}\]) by emitting an \[\alpha -\]particle with half-life of 4 days. A sample contains \[6.4\times {{10}^{10}}\]atoms of\[Rn\]. After 12 days, the number of atoms of \[{{R}_{n}}\]left in the sample will be [MP PET 1999, Pb. PMT 2004]
A)
\[3.2\times {{10}^{10}}\] done
clear
B)
\[0.53\times {{10}^{10}}\] done
clear
C)
\[2.1\times {{10}^{10}}\] done
clear
D)
\[0.8\times {{10}^{10}}\] done
clear
View Solution play_arrow
question_answer 63)
Decay constant of radium is\[\lambda \]. By a suitable process its compound radium bromide is obtained. The decay constant of radium bromide will be [MP PET 1999; JIPMER 2001, 02]
A)
\[\lambda \] done
clear
B)
More than \[\lambda \] done
clear
C)
Less than \[\lambda \] done
clear
D)
Zero done
clear
View Solution play_arrow
question_answer 64)
In the uranium radioactive series, the initial nucleus is \[_{92}{{U}^{238}}\]and the final nucleus is \[_{82}P{{b}^{206}}\]. When the uranium nucleus decays to lead, the number of \[\alpha -\]particles emitted will be [MP PMT 1999]
A)
1 done
clear
B)
2 done
clear
C)
4 done
clear
D)
8 done
clear
View Solution play_arrow
question_answer 65)
After \[1\alpha \]and \[2\beta \]emissions [CBSE PMT 1999]
A)
Mass number reduces by 3 done
clear
B)
Mass number reduces by 4 done
clear
C)
Mass number reduces by 6 done
clear
D)
Atomic number remains unchanged done
clear
View Solution play_arrow
question_answer 66)
Which of the following is a correct statement [IIT 1999; DPMT 2000; UPSEAT 2003]
A)
Beta rays are same as cathode rays done
clear
B)
Gamma rays are high energy neutrons done
clear
C)
Alpha particles are singly ionized helium atoms done
clear
D)
Protons and neutrons have exactly the same mass done
clear
View Solution play_arrow
question_answer 67)
\[^{22}Ne\]nucleus after absorbing energy decays into two \[\alpha -\]particles and an unknown nucleus. The unknown nucleus is [IIT 1999; UPSEAT 2002]
A)
Nitrogen done
clear
B)
Carbon done
clear
C)
Boron done
clear
D)
Oxygen done
clear
View Solution play_arrow
question_answer 68)
Half lives of two radioactive substances A and B are respectively 20 minutes and 40 minutes. Initially the sample of A and B have equal number of nuclei. After 80 minutes, the ratio of remaining number of A and B nuclei is [CBSE PMT 1998; JIPMER 2000]
A)
1 : 16 done
clear
B)
4 : 1 done
clear
C)
1 : 4 done
clear
D)
1 : 1 done
clear
View Solution play_arrow
question_answer 69)
A nucleus \[_{n}{{X}^{m}}\]emits one \[\alpha \] and one \[\beta \] particles. The resulting nucleus is [CBSE PMT 1998; BHU 2001; AFMC 2002]
A)
\[_{n}{{X}^{m-4}}\] done
clear
B)
\[_{n-2}{{Y}^{m-4}}\] done
clear
C)
\[_{n-4}{{Z}^{m-4}}\] done
clear
D)
\[_{n-1}{{Z}^{m-4}}\] done
clear
View Solution play_arrow
question_answer 70)
If the radioactive decay constant of radium is \[1.07\times {{10}^{-4}}\]per year, then its half life period is approximately equal to [AIIMS 1998]
A)
8,900 years done
clear
B)
7,000 years done
clear
C)
6,476 years done
clear
D)
2,520 years done
clear
View Solution play_arrow
question_answer 71)
The half-life of \[^{131}I\]is 8 days. Given a sample of \[^{131}I\]at time t = 0, we can assert that [IIT 1998]
A)
No nucleus will decay before t = 4 days done
clear
B)
No nucleus will decay before t = 8 days done
clear
C)
All nuclei will decay before t = 16 days done
clear
D)
A given nucleus may decay at any time after t = 0 done
clear
View Solution play_arrow
question_answer 72)
Carbon \[-14\]decays with half-life of about 5,800 years. In a sample of bone, the ratio of carbon \[-14\]to carbon \[-12\]is found to be \[\frac{1}{4}\] of what it is in free air. This bone may belong to a period about x centuries ago, where x is nearest to [KCET 1994]
A)
\[2\times 58\] done
clear
B)
58 done
clear
C)
58/2 done
clear
D)
\[3\times 58\] done
clear
View Solution play_arrow
question_answer 73)
Age of a tree is determined using radio-isotope of [EAMCET (Engg.) 1995]
A)
Carbon done
clear
B)
Cobalt done
clear
C)
Iodine done
clear
D)
Phosphorus done
clear
View Solution play_arrow
question_answer 74)
An atom of mass number 15 and atomic number 7 captures an \[\alpha -\]particle and then emits a proton. The mass number and atomic number of the resulting product will respectively be [SCRA 1994]
A)
14 and 2 done
clear
B)
15 and 3 done
clear
C)
16 and 4 done
clear
D)
18 and 8 done
clear
View Solution play_arrow
question_answer 75)
Which of the following statements are true regarding radioactivity (I) All radioactive elements decay exponentially with time (II) Half life time of a radioactive element is time required for one half of the radioactive atoms to disintegrate (III) Age of earth can be determined with the help of radioactive dating (IV) Half life time of a radioactive element is 50% of its average life period Select correct answer using the codes given below Codes: [SCRA 1994]
A)
I and II done
clear
B)
I, III and IV done
clear
C)
I, II and III done
clear
D)
II and III done
clear
View Solution play_arrow
question_answer 76)
In the disintegration series\[_{92}^{238}U\xrightarrow{\alpha }X\xrightarrow{\beta -}_{Z}^{A}Y\]the values of Z and A respectively will be [MP PMT 2003]
A)
92, 236 done
clear
B)
88, 230 done
clear
C)
90, 234 done
clear
D)
91, 234 done
clear
View Solution play_arrow
question_answer 77)
The particles emitted by radioactive decay are deflected by magnetic field. The particles will be [RPET 1997]
A)
Protons and \[\alpha -\]particles done
clear
B)
Electrons, protons and \[\alpha -\]particles done
clear
C)
Electrons, protons and neutrons done
clear
D)
Electrons and \[\alpha -\]particles done
clear
View Solution play_arrow
question_answer 78)
Half-life of a radioactive element is 10 days. The time during which quantity remains 1/10 of initial mass will be [RPET 1997]
A)
100 days done
clear
B)
50 days done
clear
C)
33 days done
clear
D)
16 days done
clear
View Solution play_arrow
question_answer 79)
In the given nuclear reaction A, B, C, D, E represents \[_{92}{{U}^{238}}{{\xrightarrow{\alpha }}_{B}}T{{h}^{A}}{{\xrightarrow{\beta }}_{D}}P{{a}^{C}}{{\xrightarrow{E}}_{92}}{{U}^{234}}\] [RPET 1997]
A)
A = 234, B = 90, C = 234, D = 91, E = \[\beta \] done
clear
B)
A = 234, B = 90, C = 238, D = 94, E = \[\alpha \] done
clear
C)
A = 238, B = 93, C = 234, D = 91, E = \[\beta \] done
clear
D)
A = 234, B = 90, C = 234, D = 93, E = \[\alpha \] done
clear
View Solution play_arrow
question_answer 80)
If half-life of a radioactive element is 3 hours, after 9 hours its activity becomes [RPMT 1997; RPET 1999]
A)
1/9 done
clear
B)
1/27 done
clear
C)
1/6 done
clear
D)
1/8 done
clear
View Solution play_arrow
question_answer 81)
The nucleus \[_{48}^{115}Cd\] after two successive \[{{\beta }^{-}}\] decays will give [CBSE PMT 1992; JIPMER 2000]
A)
\[_{46}^{115}Pa\] done
clear
B)
\[_{49}^{114}In\] done
clear
C)
\[_{50}^{113}Sn\] done
clear
D)
\[_{50}^{115}Sn\] done
clear
View Solution play_arrow
question_answer 82)
A radioactive sample with a half-life of 1 month has the label: ?Activity=2 micro curies on 1.8.1991.'' What will be its activity two months later [CBSE PMT 1992]
A)
1.0 micro curies done
clear
B)
0.5 micro curies done
clear
C)
4 micro curies done
clear
D)
8 micro curies done
clear
View Solution play_arrow
question_answer 83)
An element A decays into element C by a two-step process : \[A\to B+{{\ }_{2}}H{{e}^{4}}\]\[B\to C+\ 2{{e}^{-}}\] Then [CBSE PMT 1994; AMU 2002; KCET 2003]
A)
A and C are isotopes done
clear
B)
A and C are isobars done
clear
C)
A and B are isotopes done
clear
D)
A and B are isobars done
clear
View Solution play_arrow
question_answer 84)
At any instant the ratio of the amount of radioactive substances is 2 : 1. If their half lives be respectively 12 and 16 hours, then after two days, what will be the ratio of the substances [RPMT 1996]
A)
1 : 1 done
clear
B)
2 : 1 done
clear
C)
1 : 2 done
clear
D)
1 : 4 done
clear
View Solution play_arrow
question_answer 85)
Which of the following isotopes is used for the treatment of cancer [RPET 1996]
A)
\[{{K}^{40}}\] done
clear
B)
\[C{{o}^{60}}\] done
clear
C)
\[S{{r}^{90}}\] done
clear
D)
\[{{I}^{131}}\] done
clear
View Solution play_arrow
question_answer 86)
If half-life of a radioactive atom is 2.3 days, then its decay constant would be [AFMC 1997; JIPMER 2000]
A)
0.1 done
clear
B)
0.2 done
clear
C)
0.3 done
clear
D)
2.3 done
clear
View Solution play_arrow
question_answer 87)
A radioactive element \[_{90}{{X}^{238}}\]decay into\[_{83}{{Y}^{222}}\]. The number of \[\beta -\]particles emitted are [BHU 1997; JIPMER 2001, 02]
A)
4 done
clear
B)
6 done
clear
C)
2 done
clear
D)
1 done
clear
View Solution play_arrow
question_answer 88)
A radio isotope has a half life of 75 years. The fraction of the atoms of this material that would decay in 150 years will be [BHU 1997]
A)
66.6% done
clear
B)
85.5% done
clear
C)
62.5% done
clear
D)
75% done
clear
View Solution play_arrow
question_answer 89)
The activity of a radioactive sample is measured as 9750 counts per minute at t = 0 and as 975 counts per minute at t = 5 minutes. The decay constant is approximately [CBSE PMT 1997]
A)
0.230 per minute done
clear
B)
0.461 per minute done
clear
C)
0.691 per minute done
clear
D)
0.922 per minute done
clear
View Solution play_arrow
question_answer 90)
An artificial radioactive decay series begins with unstable \[_{94}^{241}Pu\]. The stable nuclide obtained after eight \[\alpha -\]decays and five \[\beta -\]decays is [SCRA 1998]
A)
\[_{83}^{209}Bi\] done
clear
B)
\[_{82}^{209}Pb\] done
clear
C)
\[_{82}^{205}Ti\] done
clear
D)
\[_{82}^{201}Hg\] done
clear
View Solution play_arrow
question_answer 91)
Consider the following two statements A. Energy spectrum of a-particles emitted in radioactive decay is discrete B. Energy spectrum of b-particles emitted in radioactive decay is continuous [AMU (Med.) 1999]
A)
Only A is correct done
clear
B)
Only B is correct done
clear
C)
A is correct but B is wrong done
clear
D)
Both A and B are correct done
clear
View Solution play_arrow
question_answer 92)
The activity of a sample is 64 × 10?5 Ci. Its half-life is 3 days. The activity will become 5 × 10?6 Ci after [MP PET 2003]
A)
12 days done
clear
B)
7 days done
clear
C)
18 days done
clear
D)
21 days done
clear
View Solution play_arrow
question_answer 93)
The half-life of radon is 3.8 days. Three forth of a radon sample decay in
A)
5.02 days done
clear
B)
15.2 days done
clear
C)
7.6 days done
clear
D)
11.4 days done
clear
View Solution play_arrow
question_answer 94)
A nucleus of an element \[_{84}{{X}^{202}}\]emits an a-particle first, a b-particle next and then a gamma photon. The final nucleus formed has an atomic number [JIPMER 1999]
A)
200 done
clear
B)
199 done
clear
C)
83 done
clear
D)
198 done
clear
View Solution play_arrow
question_answer 95)
3.8 days is the half-life period of a sample. After how many days, the sample will become 1/8th of the original substance [DCE 1999]
A)
11.4 done
clear
B)
3.8 done
clear
C)
3 done
clear
D)
None of these done
clear
View Solution play_arrow
question_answer 96)
Plutonium decays with a half-life of 24000 years. If the plutonium is stored for 72000 years, then the fraction of plutonium that remains is [CPMT 1999; MH CET 2003]
A)
\[\frac{1}{2}\] done
clear
B)
\[\frac{1}{3}\] done
clear
C)
\[\frac{1}{4}\] done
clear
D)
\[\frac{1}{8}\] done
clear
View Solution play_arrow
question_answer 97)
A radioactive substance emits [CPMT 1999]
A)
a-rays done
clear
B)
b-rays done
clear
C)
g-rays done
clear
D)
All of these done
clear
View Solution play_arrow
question_answer 98)
The large scale destruction, that would be caused due to the use of nuclear weapons is called [AFMC 1999]
A)
Nuclear holocaust done
clear
B)
Thermo-nuclear reaction done
clear
C)
Nuetron reproduction factor done
clear
D)
None of these done
clear
View Solution play_arrow
question_answer 99)
An atomic nucleus \[_{90}T{{h}^{232}}\] emits several a and b radiations and finally reduces to \[_{82}P{{b}^{208}}\]. It must have emitted [MP PET 2003]
A)
4a and 2b done
clear
B)
6a and 4b done
clear
C)
8a and 24b done
clear
D)
4a and 16b done
clear
View Solution play_arrow
question_answer 100)
In beta decay [UPSEAT 2000; MP PMT 2000]
A)
The parent and daughter nuclei have same number of protons done
clear
B)
The daughter nucleus has one proton less than the parent nucleus done
clear
C)
The daughter nucleus has one proton more than the parent nucleus done
clear
D)
The daughter nucleus has one neutron more than the parent nucleus done
clear
View Solution play_arrow
question_answer 101)
A radioactive substance has a half-life of 1 year. The fraction of this material, that would remain after 5 years will be [CPMT 2000]
A)
\[\frac{1}{32}\] done
clear
B)
\[\frac{1}{5}\] done
clear
C)
\[\frac{1}{2}\] done
clear
D)
\[\frac{4}{5}\] done
clear
View Solution play_arrow
question_answer 102)
The activity of a radioactive sample [BHU 2000]
A)
Can be increased by heating it done
clear
B)
Is independent of physical parameter done
clear
C)
Cannot be increased by any method done
clear
D)
Both (b) and (c) done
clear
View Solution play_arrow
question_answer 103)
A radioactive sample has half-life of 5 years. Probability of decay in 10 years will be [RPET 2000]
A)
100% done
clear
B)
75% done
clear
C)
50% done
clear
D)
25% done
clear
View Solution play_arrow
question_answer 104)
If half-life of a substance is 3.8 days and its quantity is 10.38 gm. Then substance quantity remaining left after 19 days will be [RPMT 2000; AFMC 2002]
A)
0.151 gm done
clear
B)
0.32 gm done
clear
C)
1.51 gm done
clear
D)
0.16 gm done
clear
View Solution play_arrow
question_answer 105)
After five half lives what will be the fraction of initial substance [RPMT 2000]
A)
\[{{\left( \frac{1}{2} \right)}^{10}}\] done
clear
B)
\[{{\left( \frac{1}{2} \right)}^{5}}\] done
clear
C)
\[{{\left( \frac{1}{2} \right)}^{4}}\] done
clear
D)
\[{{\left( \frac{1}{2} \right)}^{3}}\] done
clear
View Solution play_arrow
question_answer 106)
Which is the correct expression for half-life [CBSE PMT 2000]
A)
\[{{(t)}_{1/2}}=\log 2\] done
clear
B)
\[{{(t)}_{1/2}}=\frac{\lambda }{\log 2}\] done
clear
C)
\[{{(t)}_{1/2}}=\frac{\lambda }{\log \,\text{2}}(2.303)\] done
clear
D)
\[{{(t)}_{1/2}}=\frac{2.303\text{ log 2}}{\lambda }\] done
clear
View Solution play_arrow
question_answer 107)
A nucleus \[_{Z}^{A}X\] emits an a-particle. The resultant nucleus emits a \[{{\beta }^{+}}\]particle. The respective atomic and mass no. of the final nucleus will be [MP PET 2000]
A)
Z ? 3, A ? 4 done
clear
B)
Z ? 1, A ? 4 done
clear
C)
Z ? 2, A ? 4 done
clear
D)
Z, A ? 2 done
clear
View Solution play_arrow
question_answer 108)
What fraction of a radioactive material will get disintegrated in a period of two half-lives [MP PET 2000]
A)
Whole done
clear
B)
Half done
clear
C)
One-fourth done
clear
D)
Three-fourth done
clear
View Solution play_arrow
question_answer 109)
The activity of a radioactive sample is 1.6 curie and its half-life is 2.5 days. Its activity after 10 days will be [MP PMT 2000]
A)
0.8 curie done
clear
B)
0.4 curie done
clear
C)
0.1 curie done
clear
D)
0.16 curie done
clear
View Solution play_arrow
question_answer 110)
In a mean life of a radioactive sample [MP PMT 2000, 03]
A)
About 1/3 of substance disintegrates done
clear
B)
About 2/3 of the substance disintegrates done
clear
C)
About 90% of the substance disintegrates done
clear
D)
Almost all the substance disintegrates done
clear
View Solution play_arrow
question_answer 111)
Three fourth of the active decays in a radioactive sample in 3/4 sec. The half life of the sample is [KCET (Engg.) 2001]
A)
\[\frac{1}{2}\] sec done
clear
B)
1 sec done
clear
C)
\[\frac{3}{8}\] sec done
clear
D)
\[\frac{3}{4}\] sec done
clear
View Solution play_arrow
question_answer 112)
During mean life of a radioactive element, the fraction that disintegrates is [CPMT 2001]
A)
e done
clear
B)
\[\frac{1}{e}\] done
clear
C)
\[\frac{e-1}{e}\] done
clear
D)
\[\frac{e}{e-1}\] done
clear
View Solution play_arrow
question_answer 113)
1 Curie is equal to [BHU 2001]
A)
\[3\times {{10}^{10}}\] disintegrations/sec done
clear
B)
\[3.7\times {{10}^{7}}\] disintegrations/sec done
clear
C)
\[5\times {{10}^{7}}\] disintegrations/sec done
clear
D)
\[3.7\times {{10}^{10}}\] disintegrations/sec done
clear
View Solution play_arrow
question_answer 114)
In the given nuclear reaction, how many a and b particles are emitted \[_{92}{{X}^{235}}\to {{\ }_{82}}{{Y}^{207}}\] [AFMC 2001]
A)
3a particles and 2b particle done
clear
B)
4a particles and 3b particle done
clear
C)
6a particles and 4b particle done
clear
D)
7a particles and 4b particle done
clear
View Solution play_arrow
question_answer 115)
The electron emitted in beta radiation originates from [IIT JEE (Screening) 2001]
A)
Inner orbits of atoms done
clear
B)
Free electrons existing in nuclei done
clear
C)
Decay of a neutron in a nucleus done
clear
D)
Photon escaping from the nucleus done
clear
View Solution play_arrow
question_answer 116)
When a radioactive substance emits an a-particle, its position in the periodic table is lowered by [AIIMS 2001]
A)
One place done
clear
B)
Two places done
clear
C)
Three places done
clear
D)
Four places done
clear
View Solution play_arrow
question_answer 117)
During negative b-decay [RPET 2001]
A)
Neutron converts into proton done
clear
B)
Proton converts into neutron done
clear
C)
Neutron proton ratio increases done
clear
D)
None of these done
clear
View Solution play_arrow
question_answer 118)
Half-life is measured by [RPET 2001]
A)
Geiger-Muller counter done
clear
B)
Carbon dating done
clear
C)
Spectroscopic method done
clear
D)
Wilson-Cloud chamber done
clear
View Solution play_arrow
question_answer 119)
A radioactive nucleus emits a beta particle. The parent and daughter nuclei are [EAMCET (Engg.) 2001]
A)
Isotopes done
clear
B)
Isotones done
clear
C)
Isomers done
clear
D)
Isobars done
clear
View Solution play_arrow
question_answer 120)
If a radioactive substance reduces to \[\frac{1}{16}\] of its original mass in 40 days, what is its half-life [DCE 2001; AIIMS 2003]
A)
10 days done
clear
B)
20 days done
clear
C)
40 days done
clear
D)
None of these done
clear
View Solution play_arrow
question_answer 121)
In which of the following decay, the element does not change [MH CET (Med.) 2001]
A)
b-decay done
clear
B)
a-decay done
clear
C)
g-decay done
clear
D)
None of these done
clear
View Solution play_arrow
question_answer 122)
A radioactive nucleus with Z protons and N neutrons emits an a-particle, 2b-particles and 2 gamma rays. The number of protons and neutrons in the nucleus left after the decay respectively, are [AMU (Engg.) 2001]
A)
Z ? 3, N ? 1 done
clear
B)
Z ? 2, N ? 2 done
clear
C)
Z ? 1, N ? 3 done
clear
D)
Z, N ? 4 done
clear
View Solution play_arrow
question_answer 123)
99% of a radioactive element will decay between [AMU (Engg.) 2001]
A)
6 and 7 half lives done
clear
B)
7 and 8 half lives done
clear
C)
8 and 9 half lives done
clear
D)
9 half lives done
clear
View Solution play_arrow
question_answer 124)
1 mg gold undergoes decay with 2.7 days half-life period, amount left after 8.1 days is [UPSEAT 2001]
A)
0.91 mg done
clear
B)
0.25 mg done
clear
C)
0.5 mg done
clear
D)
0.125 mg done
clear
View Solution play_arrow
question_answer 125)
Certain radio-active substance reduces to 25% of its value in 16 days. Its half-life is [MP PMT 2001]
A)
32 days done
clear
B)
8 days done
clear
C)
64 days done
clear
D)
28 days done
clear
View Solution play_arrow
question_answer 126)
In the disintegration series \[_{92}^{238}U\xrightarrow{\alpha }x\xrightarrow{\beta }_{Z}^{A}y\] The value of Z and A respectively will be [MP PET 2001; MP PMT 2001]
A)
92, 236 done
clear
B)
88, 230 done
clear
C)
90, 234 done
clear
D)
91, 234 done
clear
View Solution play_arrow
question_answer 127)
The decay constant of a radioactive element is \[1.5\times {{10}^{-9}}\] per second. Its mean life in seconds will be [MP PET 2001]
A)
\[1.5\times {{10}^{9}}\] done
clear
B)
\[4.62\times {{10}^{8}}\] done
clear
C)
\[6.67\times {{10}^{8}}\] done
clear
D)
\[10.35\times {{10}^{8}}\] done
clear
View Solution play_arrow
question_answer 128)
The half-life of a radioactive substance against a-decay is \[1.2\times {{10}^{7}}s\]. What is the decay rate for \[4\times {{10}^{15}}\] atoms of the substance [AMU (Med.) 2002]
A)
\[4.6\times {{10}^{12}}atoms/s\] done
clear
B)
\[2.3\times {{10}^{11}}atoms/s\] done
clear
C)
\[4.6\times {{10}^{10}}atoms/s\] done
clear
D)
\[2.3\times {{10}^{8}}\] done
clear
View Solution play_arrow
question_answer 129)
10 gm of radioactive material of half-life 15 year is kept in store for 20 years. The disintegrated material is [Pb. PMT 2002]
A)
12.5 g done
clear
B)
10.5 g done
clear
C)
6.03 g done
clear
D)
4.03 g done
clear
View Solution play_arrow
question_answer 130)
In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life [KCET 2002]
A)
69.3% done
clear
B)
63% done
clear
C)
50% done
clear
D)
37% done
clear
View Solution play_arrow
question_answer 131)
The S.I. unit of radioactivity is [KCET 2002]
A)
Roentgen done
clear
B)
Rutherford done
clear
C)
Curie done
clear
D)
Becqueral done
clear
View Solution play_arrow
question_answer 132)
A radioactive material has an initial amount 16 gm. After 120 days it reduces to 1 gm, then the half-life of radioactive material is [CPMT 2003]
A)
60 days done
clear
B)
30 days done
clear
C)
40 days done
clear
D)
240 days done
clear
View Solution play_arrow
question_answer 133)
Half-life of a substance is 10 years. In what time, it becomes \[\frac{1}{4}\]th part of the initial amount [AIEEE 2002]
A)
5 years done
clear
B)
10 years done
clear
C)
20 years done
clear
D)
None of these done
clear
View Solution play_arrow
question_answer 134)
If \[{{N}_{0}}\] is the original mass of the substance of half life period \[{{T}_{1/2}}=5\] years, then the amount of substance left after 15 years is [AIEEE 2002]
A)
\[{{N}_{0}}/8\] done
clear
B)
\[{{N}_{0}}/16\] done
clear
C)
\[{{N}_{0}}/2\] done
clear
D)
\[{{N}_{0}}/4\] done
clear
View Solution play_arrow
question_answer 135)
The equation \[_{z}{{X}^{A}}\,\to {{\,}_{z+1}}{{Y}^{A}}{{+}_{-1}}{{e}^{0}}+\bar{v}\] is [CPMT 2002]
A)
b-emission done
clear
B)
a-emission done
clear
C)
e? capture done
clear
D)
Fission done
clear
View Solution play_arrow
question_answer 136)
The ratio activity of an element becomes 1/64th of its original value in 60 sec. Then the half life period is [MP PMT 2002]
A)
5 sec done
clear
B)
10 sec done
clear
C)
20 sec done
clear
D)
30 sec done
clear
View Solution play_arrow
question_answer 137)
A radioactive substance emits [MP PET 2002]
A)
Electromagnetic radiation done
clear
B)
Electrons revolving around the nucleus done
clear
C)
Charged particles done
clear
D)
Neutral particles done
clear
View Solution play_arrow
question_answer 138)
If \[_{92}{{U}^{238}}\] undergoes successively 8 a-decays and 6 b-decays, then resulting nucleus is [CBSE PMT 2002]
A)
\[_{82}{{U}^{206}}\] done
clear
B)
\[_{82}P{{b}^{206}}\] done
clear
C)
\[_{82}{{U}^{210}}\] done
clear
D)
\[_{82}{{U}^{214}}\] done
clear
View Solution play_arrow
question_answer 139)
The activity of a sample of a radioactive material is A, at time \[{{t}_{1}}\] and \[{{A}_{2}}\] at time \[{{t}_{2}}\] \[({{t}_{2}}>{{t}_{1}}).\] If its mean life T, then [BHU 2002]
A)
\[{{A}_{1}}{{t}_{1}}={{A}_{2}}{{t}_{2}}\] done
clear
B)
\[{{A}_{1}}-{{A}_{2}}={{t}_{2}}-{{t}_{1}}\] done
clear
C)
\[{{A}_{2}}={{A}_{1}}{{e}^{({{t}_{1}}-{{t}_{2}})/T}}\] done
clear
D)
\[{{A}_{2}}={{A}_{1}}{{e}^{({{t}_{1}}/{{t}_{2}})T}}\] done
clear
View Solution play_arrow
question_answer 140)
Nucleus produced due to a-decay of the nucleus \[_{Z}{{X}^{A}}\] is [MP PET 2002]
A)
\[_{Z+2}{{Y}^{A+4}}\] done
clear
B)
\[_{Z}{{Y}^{A}}\] done
clear
C)
\[_{Z-2}{{Y}^{A-4}}\] done
clear
D)
\[_{Z-4}{{Y}^{A-2}}\] done
clear
View Solution play_arrow
question_answer 141)
When \[_{90}T{{h}^{228}}\] transforms to \[_{83}B{{i}^{212}}\], then the number of the emitted a- and b-particles is, respectively [MP PET 2002]
A)
\[8\,\alpha ,\,7\beta \] done
clear
B)
\[4\,\alpha ,\,7\beta \] done
clear
C)
\[4\,\alpha ,\,4\beta \] done
clear
D)
\[4\,\alpha ,\,1\beta \] done
clear
View Solution play_arrow
question_answer 142)
Which of the following processes represents a gamma-decay [IIT-JEE (Screening) 2002]
A)
\[^{A}{{X}_{Z}}+\gamma \,\to {{\,}^{A}}{{X}_{Z-1}}+a+b\] done
clear
B)
\[^{A}{{X}_{Z}}{{+}^{1}}{{n}_{0}}\,\to {{\,}^{A-3}}{{X}_{Z-2}}+c\] done
clear
C)
\[^{A}{{X}_{Z}}\,\to {{\,}^{A}}{{X}_{Z}}+f\] done
clear
D)
\[^{A}{{X}_{Z}}+{{e}_{-1}}\,\to {{\,}^{A}}{{X}_{Z-1}}+g\] done
clear
View Solution play_arrow
question_answer 143)
The half-life of \[^{215}At\] is \[100\mu s\]. The time taken for the radioactivity of a sample of \[^{215}At\] to decay to 1/16th of its initial value is [IIT-JEE (Screening) 2002]
A)
\[400\,\mu s\] done
clear
B)
\[6.3\,\mu s\] done
clear
C)
\[40\,\mu s\] done
clear
D)
\[300\mu s\] done
clear
View Solution play_arrow
question_answer 144)
The half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its \[\frac{1}{16}\]th part [BCECE 2003]
A)
12 h done
clear
B)
16 h done
clear
C)
48 h done
clear
D)
192 h done
clear
View Solution play_arrow
question_answer 145)
A radioactive substance has an average life of 5 hours. In a time of 5 hours [Orissa JEE 2003]
A)
Half of the active nuclei decay done
clear
B)
Less than half of the active nuclei decay done
clear
C)
More than half of the active nuclei decay done
clear
D)
All active nuclei decay done
clear
View Solution play_arrow
question_answer 146)
Which of the following rays are not electromagnetic wave [CBSE PMT 2003]
A)
g-rays done
clear
B)
b-rays done
clear
C)
Heat rays done
clear
D)
X-rays done
clear
View Solution play_arrow
question_answer 147)
A sample of radioactive element has a mass of 10 gm at an instant t = 0.The approximate mass of this element in the sample after two mean lives is [CBSE PMT 2003]
A)
2.50 gm done
clear
B)
3.70 gm done
clear
C)
6.30 gm done
clear
D)
1.35 gm done
clear
View Solution play_arrow
question_answer 148)
Which of the following radiations has the least wavelength [AIEEE 2003]
A)
X-rays done
clear
B)
g-rays done
clear
C)
b-rays done
clear
D)
a-rays done
clear
View Solution play_arrow
question_answer 149)
A radioactive sample at any instant has its disintegration rate 5000 disintegration per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is [AIEEE 2003]
A)
0.8 In 2 done
clear
B)
0.4 In 2 done
clear
C)
0.2 In 2 done
clear
D)
0.1 In 2 done
clear
View Solution play_arrow
question_answer 150)
A nucleus with Z = 92 emits the following in a sequence: \[\alpha ,\,{{\beta }^{-}},\,{{\beta }^{-}},\,\alpha ,\alpha ,\alpha ,\alpha ,\alpha ,{{\beta }^{-}},\,{{\beta }^{-}},\alpha ,\,{{\beta }^{+}},\,{{\beta }^{+}},\,\alpha \]. The Z of the resulting nucleus is [AIEEE 2003]
A)
74 done
clear
B)
76 done
clear
C)
78 done
clear
D)
82 done
clear
View Solution play_arrow
question_answer 151)
Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called [AIIMS 2003]
A)
Gamma camera done
clear
B)
CAT scan done
clear
C)
Radiotracer technique done
clear
D)
Gamma ray spectroscopy done
clear
View Solution play_arrow
question_answer 152)
A radioactive decay chain starts from \[_{93}N{{p}^{237}}\] and produces \[_{90}T{{h}^{229}}\] by successive emissions. The emitted particles can be [MP PMT 2004]
A)
Two a-particles and one b-particle done
clear
B)
Three \[{{\beta }^{+}}\] particles done
clear
C)
One a particle and two \[{{\beta }^{+}}\] particles done
clear
D)
One a particle and two \[{{\beta }^{-}}\] particles done
clear
View Solution play_arrow
question_answer 153)
The half-life of a sample of a radioactive substance is 1 hour. If \[8\times {{10}^{10}}\] atoms are present at \[t=0\], then the number of atoms decayed in the duration \[t=2\] hour to \[t=4\] hour will be [MP PMT 2004]
A)
\[2\times {{10}^{10}}\] done
clear
B)
\[1.5\times {{10}^{10}}\] done
clear
C)
Zero done
clear
D)
Infinity done
clear
View Solution play_arrow
question_answer 154)
Carbon dating is best suited for determining the age of fossils if their age in years is of the order of [AIIMS 2004]
A)
\[{{10}^{3}}\] done
clear
B)
\[{{10}^{4}}\] done
clear
C)
\[{{10}^{5}}\] done
clear
D)
\[{{10}^{6}}\] done
clear
View Solution play_arrow
question_answer 155)
A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half-life of the source is [KCET 2004]
A)
120 min done
clear
B)
80 min done
clear
C)
30 min done
clear
D)
20 min done
clear
View Solution play_arrow
question_answer 156)
The half-life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after [CBSE PMT 2004]
A)
2400 years done
clear
B)
3200 years done
clear
C)
4800 years done
clear
D)
6400 years done
clear
View Solution play_arrow
question_answer 157)
Activity of radioactive element decreased to one third of original activity \[{{R}_{0}}\] in 9 years. After further 9 years, its activity will be [DCE 2002]
A)
\[{{R}_{0}}\] done
clear
B)
\[\frac{2}{3}{{R}_{0}}\] done
clear
C)
\[{{R}_{0}}/9\] done
clear
D)
\[{{R}_{0}}/6\] done
clear
View Solution play_arrow
question_answer 158)
The half-life of a radioactive substance is 40 years. How long will it take to reduce to one fourth of its original amount and what is the value of decay constant [DPMT 2003]
A)
40 year, 0.9173/year done
clear
B)
90 year, 9.017/year done
clear
C)
80 year, 0.0173 year done
clear
D)
None of these done
clear
View Solution play_arrow
question_answer 159)
The half-life of a radioactive substance is 3.6 days. How much of 20 mg of this radioactive substance will remain after 36 days [Pb. PMT 2003]
A)
0.0019 mg done
clear
B)
1.019 mg done
clear
C)
1.109 mg done
clear
D)
0.019 mg done
clear
View Solution play_arrow
question_answer 160)
A radioactive material has a half-life of 10 days. What fraction of the material would remain after 30 days [AIIMS 2005]
A)
0.5 done
clear
B)
0.25 done
clear
C)
0.125 done
clear
D)
0.33 done
clear
View Solution play_arrow
question_answer 161)
Starting with a sample of pure \[^{66}Cu,\,\frac{7}{8}\] of it decays into Zn in 15 min. The corresponding half-life is [AIEEE 2005]
A)
5 min done
clear
B)
\[7\frac{1}{2}\] min done
clear
C)
10 min done
clear
D)
15 min done
clear
View Solution play_arrow
question_answer 162)
A radioactive material has a half-life of 8 years. The activity of the material will decrease to about 1/8 of its original value in [UPSEAT 2005]
A)
256 year done
clear
B)
128 year done
clear
C)
64 year done
clear
D)
24 year done
clear
View Solution play_arrow
question_answer 163)
A nucleus decays by \[{{\beta }^{+}}\] emission followed by a gamma emission. If the atomic and mass numbers of the parent nucleus are Z and A respectively, the corresponding numbers for the daughter nucleus are respectively. [UPSEAT 2005]
A)
\[Z-1\] and \[A-1\] done
clear
B)
\[Z+1\] and \[A\] done
clear
C)
\[Z-1\] and \[A\] done
clear
D)
\[Z+1\] and \[A-1\] done
clear
View Solution play_arrow
question_answer 164)
\[_{90}^{232}Th\] an isotope of thorium decays in ten stages emitting six a-particles and four b-particles in all. The end product of the decay is [CPMT 2005]
A)
\[_{82}^{206}Pb\] done
clear
B)
\[_{82}^{209}Pb\] done
clear
C)
\[_{82}^{208}Pb\] done
clear
D)
\[_{83}^{209}Br\] done
clear
View Solution play_arrow
question_answer 165)
The composition of an a-particle can be expressed as [CPMT 2005]
A)
\[1P+1N\] done
clear
B)
\[1P+2N\] done
clear
C)
\[2P+1N\] done
clear
D)
\[2P+2N\] done
clear
View Solution play_arrow
question_answer 166)
A nucleus of mass 218 amu in free state decays to emit an a-particle. Kinetic energy of the a-particle emitted is 6.7 MeV. The recoil energy (in MeV) of the daughter nucleus is [EAMCET 2005]
A)
1.0 done
clear
B)
0.5 done
clear
C)
0.25 done
clear
D)
0.125 done
clear
View Solution play_arrow
question_answer 167)
The particle that possesses half integral spin as [EAMCET 2005]
A)
Photon done
clear
B)
Pion done
clear
C)
Proton done
clear
D)
K-meson done
clear
View Solution play_arrow
question_answer 168)
Nuclear fusion is common to the pair [MP PMT 2005]
A)
Thermonuclear reactor, uranium based nuclear reactor done
clear
B)
Energy production in sun, uranium based nuclear reactor done
clear
C)
Energy production in sun, hydrogen bomb done
clear
D)
Disintegration of heavy nuclei, hydrogen bomb done
clear
View Solution play_arrow
question_answer 169)
\[{{C}^{14}}\] has half-life 5700 years. At the end of 11400 years, the actual amount left is [MP PET 2005]
A)
0.5 of original amount done
clear
B)
0.25 of original amount done
clear
C)
0.125 of original amount done
clear
D)
0.0625 of original amount done
clear
View Solution play_arrow
question_answer 170)
Mean life of a radioactive sample is 100 seconds. Then its half-life (in minutes) is [KCET 2005]
A)
0.693 done
clear
B)
1 done
clear
C)
10-4 done
clear
D)
1.155 done
clear
View Solution play_arrow
question_answer 171)
\[_{86}{{A}^{222}}{{\to }_{84}}{{B}^{210}}\]. In this reaction how many \[\alpha \] and \[\beta \] particles are emitted [BHU 2005]
A)
\[6\alpha ,\,3\beta \] done
clear
B)
\[3\alpha ,\,4\beta \] done
clear
C)
\[4\alpha ,\,3\beta \] done
clear
D)
\[3\alpha ,\,6\beta \] done
clear
View Solution play_arrow
question_answer 172)
The phenomenon of radioactivity is [BHU 2005]
A)
Exothermic change which increases or decreases with temperature done
clear
B)
Increases on applied pressure done
clear
C)
Nuclear process does not depend on external factors done
clear
D)
None of the above done
clear
View Solution play_arrow
question_answer 173)
If half-life of radium is 77 days. Its decay constant in day will be [BCECE 2005]
A)
\[3\times {{10}^{-13}}\]/day done
clear
B)
\[9\times {{10}^{-3}}\]/day done
clear
C)
\[1\times {{10}^{-3}}\]/day done
clear
D)
\[6\times {{10}^{-3}}\]/day done
clear
View Solution play_arrow
question_answer 174)
In a radioactive reaction \[_{92}{{X}^{232}}{{\to }_{82}}{{Y}^{204}}\], the number of \[\alpha -\]particles emitted is [BCECE 2005]
A)
7 done
clear
B)
6 done
clear
C)
5 done
clear
D)
4 done
clear
View Solution play_arrow
question_answer 175)
In a sample of radioactive material, what fraction of the initial number of active nuclei will remain undisintegrated after half of a half-life of the sample [Kerala PMT 2005]
A)
\[\frac{1}{4}\] done
clear
B)
\[\frac{1}{2\sqrt{2}}\] done
clear
C)
\[\frac{1}{\sqrt{2}}\] done
clear
D)
\[2\sqrt{2}\] done
clear
View Solution play_arrow
question_answer 176)
Consider two nuclei of the same radioactive nuclide. One of the nuclei was created in a supernova explosion 5 billion years ago. The other was created in a nuclear reactor 5 minutes ago. The probability of decay during the next time is [KCET 2005]
A)
Different for each nuclei done
clear
B)
Nuclei created in explosion decays first done
clear
C)
Nuclei created in the reactor decays first done
clear
D)
Independent of the time of creation done
clear
View Solution play_arrow