Engineering Chemistry S Datta

NUCLEAR CHEMISTRY 67
29. A piece of wood was found to have 14 C/ 12 C ratio 0.7 times that in a living plant. Calculate the
approximate life period when the plant died. Given t 1/2
= 5760 years. [Ans. 2970 years]
30. A sample of uranium ore is found to contain 11.9 g of 238 U and 10.33. of 206 Pb. Calculate the age
of the rock. Given t 1/2
of uranium = 4.5 × 10 9 yrs.
[Ans. 4.5 × 10 9 years]
31. Half life of 222 Rn in 3.82 days. Calculate the weight of 1 curie of 222 Rn. [Ans. 6.5 × 10 –6 ]
32. A radioactive element disintegrates to 1/16th of its original mass in 160 days. What is its halflife
period?
[Ans. 40 days]
33. Calculate the energy released in MeV from the reaction:
10 2
11 1
5B + 1H ⎯⎯→ 5B + 1H
Given: Mass of 10 B = 10.01605 a.m.u.
Mass of 11 B = 11.01286 a.m.u.
Mass of 2H = 2.01472 a.m.u.
Mass of 1 H = 1.00812 a.m.u.
[Ans. 9.114 MeV]
34. A neutron breaks into a proton and an electron. Calculate the energy produced in MeV.
Given: Mass of neutron = 1.6747 × 10 –24 g.
Mass of proton = 1.6725 × 10 –24 g.
Mass of electron = 9 × 10 –28 g.
1 a.m.u. = 931 MeV. [Ans. 0.73 MeV]
35. Calculate the decay constant of 60 Co. Given the t 1/2
of cobalt = 5.3 years. [Ans. 0.13 yr –1 ]
36. Calculate the energy released in the nuclear fusion reaction:
2 3
4
1H + 1H ⎯⎯→ 2He
+ 0 1 n
Given: Mass of 1 2 H = 2.014 a.m.u.
Mass of 1 3 H = 3.016 a.m.u.
Mass of 2 4 He = 4.003 a.m.u.
Mass of 0 1 n = 1.009 a.m.u.
[Ans. 16.76 MeV]
37. An old wooden article shows 2.0 counts min –1 g –1 . A fresh sample of wood shows 15.2 counts
min –1 g –1 . Calculate the age of the wooden article.
Given: t 1/2
for 14 6C = 5,760 yrs. [Ans. 16,862 years]
38. Distinguish between nuclear fuel and a chemical fuel.
39. Write short note on components of a nuclear power reactor and their functions.