Radioactivity Questions and Answers

A Li target is bombarded with a proton beam currentof 10 Amp for 1hr to produce Be of activity 1 8 x 10 disc sec Assuming that one Be radioactive n cleus is produced by bombarding 1000 protons Determine the half life of Be h ob fa

c In 2 s 2 A radioactive isotope is being produced at a constant rate X Half life of the radioactive substance is Y After some time the number of radioactive nuclei become constant The value of this constant is b XY a An 2 c XY In 2 d X Y AS

Two radioactive substances x and y initially contain equal number of nuclei x has a half life of 1hour and y has a half life of 2 hours After two hours the ratio of the activity of x to that of y is 1 1 4 3 1 1 2 1 2 4 2 1

1 1 2 1 5 3 2 1 4 2 5 The fossil bone has a 14C 12C ratio which is 2002 1 16 of that in a living animal bone If the half pritlife of 4C is 5730 years then the age of the fossil bone is 1 11460 years 3 22920 years 2 17190 years 4 15840 10

6 67x 10 53 A radioactive material has mean lives of 1620 yr and 520 yr for a and emission respectively The material decays by simultaneous a and emission The time in which 1 4th of the material remains intact is a 4675 yr b 720 yr d 324 yr c 545 yr constant

A common example of decay is 15 P 32 x y 16P 32 Then x and y stand for a electron and neutrino b positron and neutrino c electron and antineutrino d positron and antineutrino

0 The plot of the number N of decayed atoms versus activity R of a radioactive substance is a c N b d R R

31 A radioactive sample has No active atoms at t 0 If the rate of disintegration at any time is R and the number of atoms is N then the ratio R N varies with time as c R N 0 b d R N O N

Suppose we consider a large number of containers each containing initially 10000 atoms of a radioactive material NCERT Exemplar with a half life of 1 yr After 1 yr a All the containers will have 5000 atoms of the material b All the containers will contain the same number of atoms of the material but that number will only be approximately 5000 c The containers will in general have different numbers of the atoms of the material but their average will be close to 5000 d None of the containers can have more than 5000 atoms ple is left undecayed after time

potential energy of electron in the 44 In a sample of radioactive material what fraction of the initial number of active nuclei will remain after half of the half life of the sample b 1 2 c 1 2 2 d 1 4 undisintegrated a 2 1 15 In a radioactive comple the fraction of initial number of

In any fission process the ratio mass of fission products mass of parent nucleus is a equal to 1 b greater than 1 c less than 1 d depends on the mass of the pare nucleus 200

If in a nuclear fusion process the masses of the fusing nuclei be m and m and the mass of the resultant nucleus be M 3 then b m3 m m l d m3 m m 2004 a m3 m m c m3 m m

22 A sample of as iodine ion was administered to a patient in a carrier consisting of 0 10 mg of stable iodine ion After 4 days 67 7 of initial radioactivity was detected in the thyroid gland of the patient The percentage of stable iodine ion that had migrated to the thyroid gland if ty for iodide ion is 8 days is 1 65 8 2 95 7 3 85 8 4 75 8

The volume occupied by an atom is greater than the volume of the nucleus by a factor of about a 10 c 10 0 b 105 d 10 5 2003 A sample of radioactive element has a mass of 10 g at an instant t 0 The approximate

A radioactive element decays by emission A detector records n beta particles in first 2 seconds and 0 8 n beta particles in next 2 seconds Find the time in which 40 of the initially present nuclei will decay A 2 n 5 4 In 5 3 B 2 n 5 3 In 5 4 C 2 n 5 3 In 5 2 2 n 5 2 D In 5 3

5 In a nuclear reactor the number of U235 nuclei undergoing fissions per second is 4 x 1020 If the energy released per fission is 250 MeV then the total energy J EAMCET 2015 released in 10 h is 1 eV 16 x 10 19 a 576 106 J c 576 10 5J b 576 10 2J d 576 10 8 J is not found in Keral