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question_answer1)
\[_{11}^{23}Na\] is the more stable isotope of Na. Find out the process by which \[_{11}^{24}Na\] can undergo radioactive decay [IIT Screening 2003]
A)
\[{{\beta }^{-}}\]emission done
clear
B)
\[\alpha \]emission done
clear
C)
\[{{\beta }^{+}}\]emission done
clear
D)
K electron capture done
clear
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question_answer2)
Oxygen contains 90% of \[{{O}^{16}}\] and 10% of \[{{O}^{18}}\]. Its atomic mass is [KCET 1998]
A)
17.4 done
clear
B)
16.2 done
clear
C)
16.5 done
clear
D)
17 done
clear
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question_answer3)
The missing particle in the reaction, \[_{92}^{235}U+_{0}^{1}n\,\to {{\,}_{56}}B{{a}^{146}}+...+3_{0}^{1}n\] is [DPMT 2001]
A)
\[_{32}^{87}Ge\] done
clear
B)
\[_{35}^{89}Br\] done
clear
C)
\[_{36}^{87}Kr\] done
clear
D)
\[_{35}^{86}Br\] done
clear
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question_answer4)
Sulphur-35 (34.96903 amu) emits a \[\beta -\]particle but no \[\gamma -\]rays, the product is chlorine-35 (34.96885 amu). The maximum energy emitted by the \[\beta -\]particle is [DPMT 2004]
A)
0.016767 MeV done
clear
B)
1.6758 MeV done
clear
C)
0.16758 MeV done
clear
D)
16.758 MeV done
clear
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question_answer5)
A radioactive substance has a constant activity of 2000 disintegration/minute. The material is separated into two fractions, one of which has an initial activity of 1000 disintegrations per second while the other fraction decays with \[{{t}_{1/2}}\]= 24 hours. The total activity in both samples after 48 hours of separation is [JIPMER 2000]
A)
2000 done
clear
B)
1250 done
clear
C)
1000 done
clear
D)
1500 done
clear
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question_answer6)
How many alpha particles are emitted per second by 1 microgram of radium
A)
\[3.62\times {{10}^{4}}/\sec \] done
clear
B)
\[0.362\times {{10}^{4}}/\sec \] done
clear
C)
\[362\times {{10}^{4}}/\sec \] done
clear
D)
\[36.2\times {{10}^{4}}/\sec \] done
clear
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question_answer7)
If 1 microgram of radium has disintegrated for 500 years, how many alpha particles will be emitted per second
A)
\[2.92\times {{10}^{4}}/\sec \] done
clear
B)
\[292\times {{10}^{4}}/\sec \] done
clear
C)
\[0.292\times {{10}^{4}}/\sec \] done
clear
D)
\[29.2\times {{10}^{4}}/\sec \] done
clear
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question_answer8)
A radioactive nucleide X decays at the rate of \[1.00\times {{10}^{5}}\] disintegration \[{{s}^{-1}}{{g}^{-1}}\]. Radium decays at the rate of \[3.70\times {{10}^{10}}\] disintegration \[{{s}^{-1}}{{g}^{-1}}\]. The activity of X in millicuries \[{{g}^{-1}}\] \[(m\,ci\,{{g}^{-1}})\] is [MP PET 2001]
A)
0.027 done
clear
B)
\[0.270\times {{10}^{-5}}\] done
clear
C)
0.00270 done
clear
D)
0.000270 done
clear
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question_answer9)
If \[_{92}{{U}^{235}}\] nucleus absorbs a neutron and disintegrates in \[_{54}X{{e}^{139}}\], \[_{38}S{{r}^{94}}\] and X, then what will be the product X [CBSE 2002]
A)
a-particle done
clear
B)
b-particle done
clear
C)
2-neutrons done
clear
D)
3-neutrons done
clear
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question_answer10)
The half-life of a radioactive isotope is 3 hours. Value of its disintegration constant is [BHU 2002]
A)
0.231 per hr done
clear
B)
2.31 per hr done
clear
C)
0.2079 per hr done
clear
D)
2.079 per hr done
clear
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question_answer11)
The activity of carbon-14 in a piece of an ancient wood is only 12.5%. If the half-life period of carbon-14 is 5760 years, the age of the piece of wood will be \[(\log \,2=0.3010)\] [MP PMT 1999]
A)
\[17.281\times {{10}^{2}}\] years done
clear
B)
\[172.81\times {{10}^{2}}\] years done
clear
C)
\[1.7281\times {{10}^{2}}\] years done
clear
D)
\[1728.1\times {{10}^{2}}\] years done
clear
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question_answer12)
The radium and uranium atoms in a sample of uranium mineral are in the ratio of \[1:2.8\times {{10}^{6}}\]. If half-life period of radium is 1620 years, the half-life period of uranium will be [MP PMT 1999]
A)
\[45.3\times {{10}^{9}}\] years done
clear
B)
\[45.3\times {{10}^{10}}\] years done
clear
C)
\[4.53\times {{10}^{9}}\] years done
clear
D)
\[4.53\times {{10}^{10}}\] years done
clear
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question_answer13)
Half-life of radium is 1580 yrs. Its average life will be [AIIMS 1999; AFMC 1999; CPMT 1999]
A)
\[2.5\times {{10}^{3}}yrs\] done
clear
B)
\[1.832\times {{10}^{3}}yrs\] done
clear
C)
\[2.275\times {{10}^{3}}yrs\] done
clear
D)
\[8.825\times {{10}^{2}}yrs\] done
clear
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question_answer14)
8 gms of a radioactive substance is reduced to \[0.5\,g\] after 1 hour. The \[{{t}_{1/2}}\] of the radioactive substance is [DCE 2000]
A)
15 min done
clear
B)
30 min done
clear
C)
45 min done
clear
D)
10 min done
clear
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question_answer15)
A first order nuclear reaction is half completed in 45 minutes. How long does it need 99.9% of the reaction to be completed [KCET 2001]
A)
5 hours done
clear
B)
7.5 hours done
clear
C)
10 hours done
clear
D)
20 hours done
clear
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question_answer16)
Number of a--particles emitted per second by a radioactive element falls to 1/32 of its original value in 50 days. The half-life-period of this elements is [AMU 2001]
A)
5 days done
clear
B)
15 days done
clear
C)
10 days done
clear
D)
20 days done
clear
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question_answer17)
What is the half-life of a radioactive substance if 87.5% of any given amount of the substance disintegrates in 40 minutes [Kerala CET 1996]
A)
160 min done
clear
B)
10 min done
clear
C)
20 min done
clear
D)
13 min 20 sec done
clear
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question_answer18)
A radioactive isotope has a \[{{t}_{1/2}}\] of 10 days. If today 125 gm of it is left, what was its weight 40 days earlier [EAMCET 1991]
A)
\[600gm\] done
clear
B)
\[1000gm\] done
clear
C)
\[1250gm\] done
clear
D)
\[2000gm\] done
clear
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question_answer19)
The half-life of \[_{6}{{C}^{14}}\], if its decay constant is \[6.31\times {{10}^{-4}}\] is [CBSE PMT 2001]
A)
1098 yrs done
clear
B)
109.8 yrs done
clear
C)
10.98 yrs done
clear
D)
1.098 yrs done
clear
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question_answer20)
A radioactive sample has a half-life of 1500 years.A sealed tube containing \[1gm\] of the sample will contain after 3000 years [MNR 1994; UPSEAT 2001, 02]
A)
\[1gm\] of the sample done
clear
B)
\[0.5gm\] of the sample done
clear
C)
\[0.25gm\] of the sample done
clear
D)
\[0.00gm\] of the sample done
clear
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question_answer21)
The half-life of a radioactive isotope is three hours. If the initial mass of the isotope were 256 g, the mass of it remaining undecayed after 18 hours would be [AIEEE 2003]
A)
4.0 g done
clear
B)
8.0 g done
clear
C)
12.0 g done
clear
D)
16.0 g done
clear
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question_answer22)
\[\frac{15}{16}th\] of a radioactive sample decays in 40 days half-life of the sample is [DCE 2001]
A)
100 days done
clear
B)
10 days done
clear
C)
1 day done
clear
D)
\[{{\log }_{e}}\]2 days done
clear
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question_answer23)
A radioactive element with half-life 6.5 hrs has \[48\times {{10}^{19}}\]atoms. Number of atoms left after 26 hrs [BHU 2003]
A)
\[24\times {{10}^{19}}\] done
clear
B)
\[12\times {{10}^{19}}\] done
clear
C)
\[3\times {{10}^{19}}\] done
clear
D)
\[6\times {{10}^{19}}\] done
clear
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question_answer24)
The half-life of 1 gm of radioactive sample is 9 hours. The radioactive decay obeys first order kinetics. The time required for the original sample to reduce to 0.2 gm is [AMU (Engg.) 2002]
A)
15.6 hours done
clear
B)
156 hours done
clear
C)
20.9 hours done
clear
D)
2.09 hours done
clear
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question_answer25)
The half-life period of a radioactive substance is 140 days. After how much time 15 g will decay from 16 g sample of it [AFMC 2002]
A)
140 days done
clear
B)
560 days done
clear
C)
280 days done
clear
D)
420 days done
clear
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question_answer26)
Percentage of a radioactive element decayed after 20 sec when half-life is 4 sec [BHU 2003]
A)
92.25 done
clear
B)
96.87 done
clear
C)
50 done
clear
D)
75 done
clear
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question_answer27)
Consider an a-particle just in contact with a \[_{92}{{U}^{238}}\]nucleus. Calculate the coulombic repulsion energy (i.e. the height of the coulombic barrier between \[{{U}_{238}}\] and alpha particle) assuming that the distance between them is equal to the sum of their radii [UPSEAT 2001]
A)
23.8517×\[{{10}^{4}}eV\] done
clear
B)
\[26.147738\times \text{1}{{\text{0}}^{\text{4}}}eV\] done
clear
C)
\[\text{25}\text{.3522}\times {{10}^{4}}eV\] done
clear
D)
\[20.2254\times {{10}^{4}}eV\] done
clear
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question_answer28)
The half-life period of \[P{{b}^{210}}\] is 22 years. If 2 gm of \[P{{b}^{210}}\] is taken, then after 11 years how much of \[P{{b}^{210}}\] will be left [KCET 2001]
A)
1.414 gm done
clear
B)
2.428 gm done
clear
C)
3.442 gm done
clear
D)
4.456 gm done
clear
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question_answer29)
A wood specimen from an archeological centre shows a \[_{6}^{14}C\] activity of 5.0 counts/min/gm of carbon. What is the age of the specimen \[({{t}_{1/2}}\]for \[_{6}^{14}C\] is 5000 years) and a freshly cut wood gives 15 counts/min/gm of carbon [AMU (Engg.) 2002]
A)
\[5.78\times {{10}^{4}}\]years done
clear
B)
\[9.85\times {{10}^{4}}\]years done
clear
C)
\[7.85\times {{10}^{3}}\]years done
clear
D)
\[0.85\times {{10}^{4}}\]years done
clear
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question_answer30)
\[_{92}{{U}^{235}}+n\to \]fission product+neutron\[+3.20\times {{10}^{-11}}J\]. The energy released when \[1g\] of \[_{92}{{U}^{235}}\] undergoes fission is [CBSE PMT 1997]
A)
\[12.75\times {{10}^{8}}kJ\] done
clear
B)
\[18.60\times {{10}^{9}}kJ\] done
clear
C)
\[8.21\times {{10}^{7}}kJ\] done
clear
D)
\[6.55\times {{10}^{6}}kJ\] done
clear
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question_answer31)
The triad of nuclei that is isotonic is [IIT 1988; DCE 2000;MP PMT 2004]
A)
\[_{6}{{C}^{14}},{{\,}_{7}}{{N}^{15}},{{\,}_{9}}{{F}^{17}}\] done
clear
B)
\[_{6}{{C}^{12}},{{\,}_{7}}{{N}^{14}},{{\,}_{9}}{{F}^{19}}\] done
clear
C)
\[_{6}{{C}^{14}},{{\,}_{7}}{{N}^{14}},{{\,}_{9}}{{F}^{17}}\] done
clear
D)
\[_{6}{{C}^{14}},{{\,}_{7}}{{N}^{14}}{{,}_{9}}{{F}^{19}}\] done
clear
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question_answer32)
The relative abundance of two isotopes of atomic weight 85 and 87 is 75% and 25% respectively. The average atomic weight of element is [DCE 2003]
A)
75.5 done
clear
B)
85.5 done
clear
C)
40.0 done
clear
D)
86.0 done
clear
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