12th Class Chemistry Nuclear Chemistry / नाभिकीय रसायन Question Bank

done Critical Thinking Nuclear chemistry Total Questions - 32

• 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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