JEE Main & Advanced Chemistry Surface & Nuclear Chemistry / भूतल और नाभिकीय रसायन Question Bank

done Rate of decay and Half-life Total Questions - 84

• question_answer1)
  The half-life period of a radioactive substance is 8 years. After 16 years, the mass of the substance will reduce from starting \[16.0g\] to         [MP PMT 1999]
  A)
                  \[8.0\,g\]             done clear
  B)
                  \[6.0\,g\] done clear
  C)
                  \[4.0\,g\] done clear
  D)
                  \[2.0\,g\] done clear
  View Solution play_arrow

• question_answer2)
  The atomic mass of an element is 12.00710 amu. If there are 6 neutrons in the nucleus of the atom of the element, the binding energy per nucleon of the nucleus will be [MP PMT 1999]
  A)
                  7.64 MeV             done clear
  B)
                  76.4 MeV done clear
  C)
                  764 MeV              done clear
  D)
                  0.764 MeV (\[{{e}^{-}}\]=0.00055 amu, \[p\]=1.00814 amu, \[n\]=1.00893 amu) done clear
  View Solution play_arrow

• question_answer3)
  Half-life period of a metal is 20 days. What fraction of metal does remain after 80 days   [BHU 1996]
  A)
                  1              done clear
  B)
                  1/16 done clear
  C)
                  1/4         done clear
  D)
                  1/8 done clear
  View Solution play_arrow

• question_answer4)
  In the radioactive decay \[_{92}{{X}^{232}}\to {{\,}_{89}}{{Y}^{220}}\], how many \[\alpha \] and \[\beta \]- particles are ejected from \[X\] to form \[Y\] [CBSE 1999]
  A)
                  \[3\alpha \] and \[3\beta \]         done clear
  B)
                  \[5\alpha \] and \[3\beta \] done clear
  C)
                  \[3\alpha \] and \[5\beta \]         done clear
  D)
                  \[5\alpha \] and \[5\beta \] done clear
  View Solution play_arrow

• question_answer5)
  Which of the following does not take place by \[\alpha \]- decay [MP PMT 1996]
  A)
                  \[_{92}{{U}^{238}}\xrightarrow{{}}{{\,}_{90}}T{{h}^{234}}\]         done clear
  B)
                  \[_{90}T{{h}^{232}}\xrightarrow{{}}{{\,}_{88}}R{{a}^{228}}\] done clear
  C)
                  \[_{88}R{{a}^{226}}\xrightarrow{{}}{{\,}_{86}}R{{n}^{222}}\] done clear
  D)
                  \[_{83}B{{i}^{213}}\xrightarrow{{}}{{\,}_{84}}P{{o}^{213}}\] done clear
  View Solution play_arrow

• question_answer6)
  \[1.0g\] of a radioactive isotope was found to reduce to \[125\,mg\] after 24 hours. The half-life of the isotope is             [MP PET 1996]
  A)
                  8 hours done clear
  B)
                  24 hours done clear
  C)
                  6 hours done clear
  D)
                  4 hours done clear
  View Solution play_arrow

• question_answer7)
  A radioactive element decays at such a rate that after 15 minutes only 1/10 of the original amount is left. How many more minutes will be needed when only 1/100 of the original amount will be left
  A)
                  1.5 minutes        done clear
  B)
                  15.0 mintues done clear
  C)
                  16.5 minutes      done clear
  D)
                  30 minutes done clear
  View Solution play_arrow

• question_answer8)
  The radioactive decay of \[_{35}{{X}^{88}}\] by a beta emission produces an unstable nucleus which spontaneously emits a neutron. The final product is       [MNR 1995; CBSE 2001]
  A)
                  \[_{37}{{X}^{88}}\]          done clear
  B)
                  \[_{35}{{Y}^{89}}\] done clear
  C)
                  \[_{34}{{Z}^{88}}\]          done clear
  D)
                  \[_{36}{{W}^{87}}\] done clear
  View Solution play_arrow

• question_answer9)
  What is the half-life of a radioactive substance if 75% of a given amount of the substance disintegrates in 30 minutes
  A)
                  7.5 minutes        done clear
  B)
                  25 minutes done clear
  C)
                  20 minutes          done clear
  D)
                  15 minutes done clear
  View Solution play_arrow

• question_answer10)
  In radioactive decay which one of the following moves the fastest           [MP PET/PMT 1998]
  A)
                  \[\alpha \]-particle          done clear
  B)
                  \[\beta \]-particle done clear
  C)
                  \[\gamma \]-rays             done clear
  D)
                  Positron done clear
  View Solution play_arrow

• question_answer11)
  The half-life of a radionuclide is 69.3 minutes. What is its average life (in minutes)
  A)
                  100         done clear
  B)
                  \[{{10}^{-2}}\] done clear
  C)
                  \[{{(69.3)}^{-1}}\] done clear
  D)
                  \[0.693\times 69.3\] done clear
  View Solution play_arrow

• question_answer12)
  \[10gm\] of a radioactive substance is reduced to \[1.25gm\] after 15 days. Its \[1kg\] mass will reduce (in how many days) to \[500gm\] in
  A)
                  500 days               done clear
  B)
                  125 days done clear
  C)
                  25 days done clear
  D)
                  5 days done clear
  View Solution play_arrow

• question_answer13)
  A radioactive isotope having a half-life of 3 days was received after 12 days. It was found that there were 3 gm of the isotope in the container. The initial weight of the isotope when packed was [NCERT 1980; CPMT 1999; KCET 2000; Pb.CET 2001]
  A)
                  12 gm    done clear
  B)
                  24 gm done clear
  C)
                  36 gm    done clear
  D)
                  48 gm done clear
  View Solution play_arrow

• question_answer14)
  \[{{C}^{14}}\] is radioactive. The activity and the disintegration product are
  A)
                  \[\beta \]-active,  \[_{7}{{N}^{14}}\]       done clear
  B)
                   \[\alpha \]- active,  \[_{7}B{{e}^{10}}\] done clear
  C)
                  Positron active, \[_{5}{{B}^{14}}\]            done clear
  D)
                   \[\gamma \]- active,  \[{{C}^{14}}\] done clear
  View Solution play_arrow

• question_answer15)
  Radioactivity of a radioactive element remains \[\frac{1}{10}\] of the original radioactivity after 2.303 seconds. The half-life period is                                               [CPMT 1985]
  A)
                  2.303     done clear
  B)
                  0.2303 done clear
  C)
                  0.693     done clear
  D)
                  0.0693 done clear
  View Solution play_arrow

• question_answer16)
  A radioactive substance has \[{{t}_{1/2}}\]60 minutes. After 3 hrs, what percentage of radioactive substance will remain [BHU 1995]
  A)
                  50%        done clear
  B)
                  75% done clear
  C)
                  25%        done clear
  D)
                  12.5% done clear
  View Solution play_arrow

• question_answer17)
  A freshly prepared radioactive source of half-life 2 hours emits radiations of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is [IIT 1988]
  A)
                  6 hours done clear
  B)
                  12 hours done clear
  C)
                  24 hours               done clear
  D)
                  128 hours done clear
  View Solution play_arrow

• question_answer18)
  During a negative \[\beta \]-decay          [MNR 1990; IIT 1985]
  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 of the nucleus is converted into an electron done clear
  View Solution play_arrow

• question_answer19)
  The decay constant of a radioactive sample is \['\lambda '\]. The half-life and mean life of the sample are respectively [MNR 1990; IIT 1989]
  A)
                  \[\frac{1}{\lambda },\,\frac{\ln \,2}{\lambda }\]                 done clear
  B)
                  \[\frac{\ln \,2}{\lambda },\,\frac{1}{\lambda }\] done clear
  C)
                  \[\lambda \,\ln \,2,\,\frac{1}{\lambda }\]              done clear
  D)
                  \[\frac{\lambda }{\ln \,2},\,\frac{1}{\lambda }\] done clear
  View Solution play_arrow

• question_answer20)
  The half-life of a radio isotope is 20 hours. After 60 hours, how much amount will be left behind [MP PMT 1991]
  A)
                  1/8         done clear
  B)
                  1/4 done clear
  C)
                  1/3         done clear
  D)
                  ½ done clear
  View Solution play_arrow

• question_answer21)
  Half-life period of a zero order reaction is [AMU (Engg.) 1999]
  A)
                  Inversely proportional to the concentration done clear
  B)
                  Independent of the concentration done clear
  C)
                          Directly proportional to the initial concentration done clear
  D)
                  Directly proportional to the final concentration done clear
  View Solution play_arrow

• question_answer22)
  If 12 g of sample is taken, and 6 g of a sample decays in 1 hr. The amount of sample showing decay in next hour is [AMU (Engg.) 1999]
  A)
                  3 g done clear
  B)
                  1 g done clear
  C)
                  2 g          done clear
  D)
                  6 g done clear
  View Solution play_arrow

• question_answer23)
  What will be half-life period of a nucleus if at the end of 4.2 days, \[N=0.798\,{{N}_{0}}\]              [MP PET 2000]
  A)
                  15 days done clear
  B)
                  10 days done clear
  C)
                  12.83 days           done clear
  D)
                  20 days done clear
  View Solution play_arrow

• question_answer24)
  If 2.0 g of a radioactive substance has half-life of 7 days. The half-life of 1 g sample is      [MP PET 2000]
  A)
                  7 days   done clear
  B)
                  14 days done clear
  C)
                  28 days done clear
  D)
                  35 days done clear
  View Solution play_arrow

• question_answer25)
  The half-life of \[_{38}^{90}Sr\] is 20 years. If its sample having initial activity of 8000 dis/min is taken, what would be its activity after 80 years                                     [MP PMT 2000]
  A)
                  500 dis/min         done clear
  B)
                  800 dis/min done clear
  C)
                  1000 dis/min      done clear
  D)
                  1600 dis/min done clear
  View Solution play_arrow

• question_answer26)
  \[_{11}N{{a}^{24}}\] half-life is 15 hours. On heating it will
  A)
                  Reduce                 done clear
  B)
                  Remain unchanged done clear
  C)
                  Depend on temperature              done clear
  D)
                  Become double done clear
  View Solution play_arrow

• question_answer27)
  In a radioactive decay, an emitted electron comes from [CBSE 1994; Pb. PET 1999]
  A)
                  Nucleus of the atom done clear
  B)
                  Inner orbital of the atom done clear
  C)
                  Outermost orbit of the atom done clear
  D)
                  Orbit having principal quantum number one done clear
  View Solution play_arrow

• question_answer28)
  What is the value of decay constant of a compound having half-life time \[{{T}_{1/2}}=2.95\] days            [AFMC 1997]
  A)
                  \[2.7\times {{10}^{-5}}{{s}^{-1}}\]            done clear
  B)
                  \[2.7\times {{10}^{6}}{{s}^{-1}}\] done clear
  C)
                  \[2.7\times {{10}^{-6}}{{s}^{-1}}\]            done clear
  D)
                  \[3\times {{10}^{5}}{{s}^{-1}}\] done clear
  View Solution play_arrow

• question_answer29)
  What kind of radioactive decay does not lead to the formation of a daughter nucleus that is an isobar of the parent nucleus                                                [JIPMER 1999]
  A)
                  a-rays   done clear
  B)
                  b-rays done clear
  C)
                  Positron               done clear
  D)
                  Electron capture done clear
  View Solution play_arrow

• question_answer30)
  The half-life of \[_{6}{{C}^{14}}\] if its K or \[\lambda \] is \[2.31\times {{10}^{-4}}\] is [BHU 1999]
  A)
                  \[2\times {{10}^{2}}yrs\]              done clear
  B)
                  \[3\times {{10}^{3}}yrs\] done clear
  C)
                  \[3.5\times {{10}^{4}}yrs\]           done clear
  D)
                  \[4\times {{10}^{3}}yrs\] done clear
  View Solution play_arrow

• question_answer31)
  A radioactive isotope has a half-life of 10 days. If today \[125\,mg\]is left over, what  was its original weight 40 days earlier                [KCET 2005]
  A)
                  2g           done clear
  B)
                  600 mg done clear
  C)
                  1 g          done clear
  D)
                  1.5 g done clear
  View Solution play_arrow

• question_answer32)
  The binding energy of \[_{8}{{O}^{16}}\] is 127 MeV. Its binding energy per neutron is                                   [MH CET 1999]
  A)
                  0.794 MeV           done clear
  B)
                  1.5875 MeV done clear
  C)
                  7.94 MeV             done clear
  D)
                  15.875 MeV done clear
  View Solution play_arrow

• question_answer33)
  If the half-life period of a first order reaction is 138.6 minutes, then the value of decay constant for the reaction will be [MH CET 1999]
  A)
                  5 minute?1           done clear
  B)
                  0.5 minute?1 done clear
  C)
                  0.05 minute?1     done clear
  D)
                  0.005 minute?1 done clear
  View Solution play_arrow

• question_answer34)
  Half-life of \[10gm\] of radioactive substance is 10 days. The half-life of \[20gm\] is                                          [CPMT 1996]
  A)
                  10 days done clear
  B)
                  20 days done clear
  C)
                  25 days done clear
  D)
                  Infinite done clear
  View Solution play_arrow

• question_answer35)
  \[8gm\] of the radioactive isotope, cesium-137 were collected on February 1 and kept in a sealed tube. On July 1, it was found that only \[0.25gm\] of it remained. So the half-life period of the isotope is            [KCET 1989]
  A)
                  37.5 days             done clear
  B)
                  30 days done clear
  C)
                  25 days done clear
  D)
                  50 days done clear
  View Solution play_arrow

• question_answer36)
  The half-life of radium (226) is 1620 years. The time taken to convert 10 grams of radium to 1.25 grams is [MP PET 1994; UPSEAT 2001]
  A)
                  810 years             done clear
  B)
                  1620 years done clear
  C)
                  3240 years           done clear
  D)
                  4860 years done clear
  View Solution play_arrow

• question_answer37)
  Half-life of a radioactive substance is 120 days. After 480 days, 4 gm will be reduced to   [EAMCET 1993]
  A)
                  2              done clear
  B)
                  1 done clear
  C)
                  0.5          done clear
  D)
                  0.25 done clear
  View Solution play_arrow

• question_answer38)
  The half-life of \[C{{o}^{60}}\] is  7 years. If one \[gm\] of it decays, the amount of the substance remaining after 28 years  is [EAMCET 1992]
  A)
                  \[0.25\,gm\]       done clear
  B)
                  \[0.125\,gm\] done clear
  C)
                  \[0.0625\,gm\]  done clear
  D)
                  \[0.50\,gm\] done clear
  View Solution play_arrow

• question_answer39)
  A radioactive isotope decays at such a rate that after 96 minutes only \[\frac{1}{8}th\] of the original amount remains. The half-life of this nuclide in minutes is         [KCET 1992]
  A)
                  12           done clear
  B)
                  24 done clear
  C)
                  32           done clear
  D)
                  48 done clear
  View Solution play_arrow

• question_answer40)
  \[C-14\] has a half-life of 5760 years. \[100mg\]  of a sample containing \[C-14\] is reduced to \[25mg\] in [Bihar CEE 1992; AMU 2002; MHCET 1999]
  A)
                  11520 years        done clear
  B)
                  2880 years done clear
  C)
                  1440 years           done clear
  D)
                  17280 years done clear
  View Solution play_arrow

• question_answer41)
  Half-life of a radioactive element is 100 yrs. The time in which it disintegrates to 50% of its mass, will be [MP PMT 1995]
  A)
                  50 yrs    done clear
  B)
                  200 yrs done clear
  C)
                  100 yrs  done clear
  D)
                  25 yrs done clear
  View Solution play_arrow

• question_answer42)
  The average life period of a radioactive element is the reciprocal of its                                   [MP PET 1995]
  A)
                  Half-life period done clear
  B)
                  Disintegration constant done clear
  C)
                  Number of atoms present at any time done clear
  D)
                  Number of neutrons done clear
  View Solution play_arrow

• question_answer43)
  The half-life period of a radioactive element is 30 minutes. One sixteenth of the original quantity of the element will remain unchanged after              [CPMT 1983; MP PMT 1994]
  A)
                  60 minutes          done clear
  B)
                  120 minutes done clear
  C)
                  70 minutes          done clear
  D)
                  75 minutes done clear
  View Solution play_arrow

• question_answer44)
  For a radioactive substance with half-life period 500 years, the time for complete decay of 100 milligram of it would be  [MADT Bihar 1984]
  A)
                  1000 years           done clear
  B)
                  \[100\times 500\] years done clear
  C)
                  500 years             done clear
  D)
                  Infinite time done clear
  View Solution play_arrow

• question_answer45)
  A substance of which one gram is taken, after half-life time what fraction of it is left ?    [MADT Bihar 1983]
  A)
                  \[\frac{1}{4}\]    done clear
  B)
                  \[\frac{1}{8}\] done clear
  C)
                  \[\frac{1}{2}\]    done clear
  D)
                  \[\frac{1}{32}\] done clear
  View Solution play_arrow

• question_answer46)
  The half-life of the radio element  \[_{83}B{{i}^{210}}\] is 5 days. Starting with 20 g of this isotope, the amount remaining after 15 days is                                  [BHU 1987]
  A)
                  10 g        done clear
  B)
                  5 g done clear
  C)
                  2.5 g       done clear
  D)
                  6.66 g done clear
  View Solution play_arrow

• question_answer47)
  In radioactive decay of X into Y below,  \[_{Z}{{Y}^{m}}\] is                 \[_{6}{{X}^{14}}\xrightarrow{-3\beta }{{\,}_{Z}}{{Y}^{m}}\]         
  A)
                  \[_{6}{{Y}^{15}}\]             done clear
  B)
                  \[_{7}{{Y}^{17}}\] done clear
  C)
                  \[_{9}{{Y}^{14}}\]            done clear
  D)
                  \[_{8}{{Y}^{14}}\] done clear
  View Solution play_arrow

• question_answer48)
  75% of the first order reaction was completed in 32 minutes. When was 50% of the reaction completed [MNR 1983; MP PET 1997; EAMCET 1998]
  A)
                  24 minutes          done clear
  B)
                  16 minutes done clear
  C)
                  8 minutes            done clear
  D)
                  4 minutes done clear
  View Solution play_arrow

• question_answer49)
  If \[2.0\,g\] of a radioactive isotope has a half-life of 20 hr, the half-life of \[0.5g\] of the same substance is [MP PMT 1990; MNR 1992]
  A)
                  20 hr      done clear
  B)
                  80 hr done clear
  C)
                  5  hr       done clear
  D)
                  10 hr done clear
  View Solution play_arrow

• question_answer50)
  Radioactive lead \[_{82}P{{b}^{201}}\] has a half-life of 8 hours. Starting from one milligram of this isotope, how much will remain after 24 hours    [MP PMT 1990]
  A)
                  \[1/2\ mg\]         done clear
  B)
                  \[1/3\,mg\]  done clear
  C)
                  \[1/8\,mg\]        done clear
  D)
                  \[1/4\,mg\] done clear
  View Solution play_arrow

• question_answer51)
  The half-life of \[_{92}{{U}^{238}}\] is \[4.5\times {{10}^{9}}\] years. After how many years, the amount of \[_{92}{{U}^{238}}\] will be reduced to half of its present amount              [CPMT 1990; MP PET 1999]
  A)
                  \[9.0\times {{10}^{9}}\] years     done clear
  B)
                  \[13.5\times {{10}^{9}}\] years done clear
  C)
                  \[4.5\times {{10}^{9}}\] years     done clear
  D)
                  \[4.5\times {{10}^{4.5}}\] years done clear
  View Solution play_arrow

• question_answer52)
  Radium has atomic weight 226 and a half-life of 1600 years. The number of disintegrations produced per second from \[1gm\] are        [BHU 1990]
  A)
                  \[4.8\times {{10}^{10}}\]              done clear
  B)
                  \[9.2\times {{10}^{6}}\] done clear
  C)
                  \[3.7\times {{10}^{10}}\] done clear
  D)
                  Zero done clear
  View Solution play_arrow

• question_answer53)
  The half-life of a radioactive element is 6 months. The time taken to reduce its original concentration to its 1/16 value is [MP PET 1991]
  A)
                  1 year    done clear
  B)
                  16 years done clear
  C)
                  2 years  done clear
  D)
                  8 years done clear
  View Solution play_arrow

• question_answer54)
  In the case of a radio isotope the value of \[{{T}_{1/2}}\] and l are identical in magnitude. The value is     [KCET 2002]
  A)
                  \[0.693\]              done clear
  B)
                  \[{{(0.693)}^{1/2}}\] done clear
  C)
                  \[1/0.693\]          done clear
  D)
                  \[{{(0.693)}^{2}}\] done clear
  View Solution play_arrow

• question_answer55)
  A radioactive element has half-life of one day. After three days, the amount of the element left will be [MNR 1985; UPSEAT 2000, 01; MH CET 2002]
  A)
                  1/2 of the original amount done clear
  B)
                  1/4 of the original amount done clear
  C)
                  1/8 of the original amount done clear
  D)
                  1/16 of the original amount done clear
  View Solution play_arrow

• question_answer56)
  The radioactivity due to \[{{C}^{14}}\] isotope (half-life 6000 years) of a sample of wood from an ancient tomb was found to be nearly half that of fresh wood, the tomb is therefore about [NCERT 1980, 81; MP PET 1989]
  A)
                  3000 years old   done clear
  B)
                  6000 years old done clear
  C)
                  9000 years old   done clear
  D)
                  1200 years old done clear
  View Solution play_arrow

• question_answer57)
  The decay of a radioactive element follows first order kinetics, as a result                                             [NCERT 1982]
  A)
                  Half-life period = constant \[/k\], where \[k\] is the decay constant done clear
  B)
                  Rate of decay is independent of temperature done clear
  C)
                  Rate can be changed by changing chemical conditions done clear
  D)
                  The element will be completely transformed into a new element after expiry of two half-life period done clear
  View Solution play_arrow

• question_answer58)
  Half-life of a radioactive substance which disintegrates by 75 % in 60 minutes, will be         [MP PMT 2002]
  A)
                  120 min                done clear
  B)
                  30 min done clear
  C)
                  45 min   done clear
  D)
                  20 min done clear
  View Solution play_arrow

• question_answer59)
  87.5% decomposition of a radioactive substance complete in 3 hours. What is the half-life of that substance        [MP PMT 2003]
  A)
                  2 hours                 done clear
  B)
                  3 hours done clear
  C)
                  90 minutes          done clear
  D)
                  1 hours done clear
  View Solution play_arrow

• question_answer60)
  Tritium undergoes radioactive decay giving [CPMT 1976; NCERT 1978]
  A)
                  \[\alpha \]-particles        done clear
  B)
                  \[\beta \]-particles done clear
  C)
                  Neutrons             done clear
  D)
                  None of these done clear
  View Solution play_arrow

• question_answer61)
  Given that a radioactive species decays according to exponential law \[N={{N}_{0}}{{e}^{-\lambda t}}\]. The half-life of the species is [Kerala (Med.) 2003]
  A)
                  \[\lambda \]       done clear
  B)
                  \[No\] done clear
  C)
                  \[\lambda /\ln 2\]            done clear
  D)
                  \[\ln 2/\lambda \] done clear
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• question_answer62)
  Half-life of a radioactive disintegration (A \[\to \]B) having rate constant \[231\,{{\sec }^{-1}}\] is              [CPMT 1988]
  A)
                  \[3.0\times {{10}^{-2}}\] sec        done clear
  B)
                  \[3.0\times {{10}^{-3}}\] sec done clear
  C)
                  \[3.3\times {{10}^{-2}}\] sec        done clear
  D)
                  \[3.3\times {{10}^{-3}}\] sec done clear
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• question_answer63)
  The amount of \[_{53}{{I}^{128}}\]  \[{{t}_{1/2}}=25\] minutes) left after 50 minutes will be         [AIIMS 1982; DPMT 1982, 83]
  A)
                  One ? half           done clear
  B)
                  One ? third done clear
  C)
                  One ? fourth      done clear
  D)
                  Nothing done clear
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• question_answer64)
  If 3/4  quantity of a radioactive element disintegrates in two hours, its half-life would be [MP PMT 1989; CPMT 1984]
  A)
                  1 hour   done clear
  B)
                  45 minutes done clear
  C)
                  30 minutes          done clear
  D)
                  15 minutes done clear
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• question_answer65)
  Radioactive decay is a    [MP PMT 1989, 97]
  A)
                  Second order reaction   done clear
  B)
                  First order reation done clear
  C)
                  Zero order reaction         done clear
  D)
                  Third order reaction done clear
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• question_answer66)
  The half-life of a radioactive element depends upon [EAMCET 1980]
  A)
                  The amount of the element done clear
  B)
                  The temperature done clear
  C)
                  The pressure done clear
  D)
                  None of these done clear
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• question_answer67)
  The activity of radio isotope changes with            [MNR 1986]
  A)
                  Temperature     done clear
  B)
                  Pressure done clear
  C)
                  Chemical environment  done clear
  D)
                  None of these done clear
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• question_answer68)
  A certain nuclide has a half-life of 25 minutes. If one starts with 100 g of it, how much of it will remain at the end of 100 minutes                                               [DPMT 1982]
  A)
                  1.0 g      done clear
  B)
                  4.0 g done clear
  C)
                  6.25 g    done clear
  D)
                  12.50 g done clear
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• question_answer69)
  If \[{{U}^{235}}\] is bombarded with neutrons, atom will split into [CPMT 1981]
  A)
                  Sr + Pb  done clear
  B)
                  Cs + Rb done clear
  C)
                  Kr + Cd  done clear
  D)
                  Ba + Kr done clear
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• question_answer70)
  If 8.0 of a radioactive isotope has a half-life of 10 hrs. The half-life of 2.0 g of the same substance is          [UPSEAT 2001]
  A)
                  2.5 hrs.                 done clear
  B)
                  5 hrs. done clear
  C)
                  10 hrs.   done clear
  D)
                  40 hrs. done clear
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• question_answer71)
  If the disintegration constant is \[6.93\times {{10}^{-6}},\] then half-life of \[_{6}{{C}^{14}}\] will be                                        [KCET 2001]
  A)
                  \[{{10}^{2}}\]yrs               done clear
  B)
                  \[{{10}^{3}}\]yrs done clear
  C)
                  \[{{10}^{4}}\]yrs               done clear
  D)
                  \[{{10}^{5}}\]yrs done clear
  View Solution play_arrow

• question_answer72)
  The decay constant of \[R{{a}^{226}}\] is \[1.37\times {{10}^{-11}}{{\sec }^{-1}}\]. A sample of  \[R{{a}^{226}}\] having an activity of 1.5 millicurie will contain ...... atoms
  A)
                  \[4.1\times {{10}^{18}}\]              done clear
  B)
                  \[3.7\times {{10}^{17}}\] done clear
  C)
                  \[2.05\times {{10}^{15}}\]            done clear
  D)
                  \[4.7\times {{10}^{10}}\] done clear
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• question_answer73)
  Amount of \[_{53}{{I}^{128}}({{t}_{1/2}}=25\ \min )\] left after 75 minutes is [DCE 2002]
  A)
                  \[1/6\]  done clear
  B)
                  \[1/4\] done clear
  C)
                  \[1/8\]  done clear
  D)
                  \[1/9\] done clear
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• question_answer74)
  The half-life of a radioisotope is four hours. If the initial mass of the isotope was 200 g, the mass remaining after 24 hours undecayed is                                     [AIEEE 2004]
  A)
                  3.125 g  done clear
  B)
                  2.084 g done clear
  C)
                  1.042 g  done clear
  D)
                  4.167 g done clear
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• question_answer75)
  An artificial radioactive isotope gave \[_{7}^{14}N\]after two successive \[\beta -\]particle emissions. The number of neutrons in the parent nucleus must be                                                [KCET 2004]
  A)
                  9              done clear
  B)
                  14 done clear
  C)
                  5              done clear
  D)
                  7 done clear
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• question_answer76)
  If the half-life of an isotope X is 10 years, its decay constant is [DCE 2004]
  A)
                  \[6.932\ y{{r}^{-1}}\]      done clear
  B)
                  \[0.6932\ y{{r}^{-1}}\] done clear
  C)
                  \[0.06932\ y{{r}^{-1}}\]  done clear
  D)
                  \[0.006932\ y{{r}^{-1}}\]                 done clear
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• question_answer77)
  A radioactive isotope decays at such a rate that after 192 minutes only \[1/16\] of the original amount remains. The half-life of the radioactive isotope is [Kerala CET 2004]
  A)
                  32 min   done clear
  B)
                  48 min done clear
  C)
                  12 min   done clear
  D)
                  24 min done clear
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• question_answer78)
  In the given reaction, \[_{92}{{U}^{235}}\xrightarrow{-\alpha }(A)\xrightarrow{-\beta }(B)\xrightarrow{-\beta }(C)\]  isotope are                 [Pb. CET 2000]
  A)
                  A and C done clear
  B)
                  \[_{92}{{U}^{235}}\]and C done clear
  C)
                  A and B done clear
  D)
                  A, B and C done clear
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• question_answer79)
  Rate constant for a reaction is \[\lambda \]. Average life is representative by                                      [Orissa JEE 2004]
  A)
                  \[1/\lambda \]  done clear
  B)
                  \[\text{In}2/\lambda \] done clear
  C)
                  \[\frac{\lambda }{\sqrt{2}}\]       done clear
  D)
                  \[\frac{0.693}{\lambda }\] done clear
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• question_answer80)
  For a reaction, the rate constant is \[2.34{{\sec }^{-1}}\]. The half-life period for the reaction is
  A)
                  0.30 sec                done clear
  B)
                  0.60 sec done clear
  C)
                  3.3 sec   done clear
  D)
                  Data is insufficient done clear
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• question_answer81)
  \[{{T}_{1/2}}\] of \[{{C}^{14}}\] isotope is 5770 years. time after which 72% of isotope left is        [Orissa JEE 2005]
  A)
                  2740 years           done clear
  B)
                  274 years done clear
  C)
                  2780 years           done clear
  D)
                  278 years done clear
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• question_answer82)
  A radioactive substance takes 20 min to decay 25%. How much time will be taken to decay 75%                 [Orissa JEE 2005]
  A)
                  96.4 min               done clear
  B)
                  68 min done clear
  C)
                  964 min                done clear
  D)
                  680 min done clear
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• question_answer83)
  A radioactive sample is emitting 64 times radiations than nonhazardous limit. if its half-life is 2 hours, after what time it becomes non-hazardous              [DPMT 2005]
  A)
                  16 hr      done clear
  B)
                  12 hr done clear
  C)
                  8 hr        done clear
  D)
                  4 hr done clear
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• question_answer84)
  If 8.0 g of a radioactive substance has a half-life of 10 hrs., the half-life of 2.0 g of the same substance is                [J & K 2005]
  A)
                  2.6 hr     done clear
  B)
                  5 hr done clear
  C)
                  10 hr      done clear
  D)
                  40 hr done clear
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