Engineering Chemistry S Datta

66 ENGINEERING CHEMISTRY
4. What are α-, β- and γ-rays? Compare their ionising power, range and velocity.
5. Explain the terms:
(i) Disintegration constant
(ii) Half-life period
6. What are the units of radioactivity?
7. Give a relation between half-life and the decay constant of a radioactive substance.
8. What are the causes of nuclear instability? Explain with suitable examples.
9. State and explain the law of radioactive disintegration. What do you mean by the half-life period
of a radioactive element? Show that the half-life is independent of the amount of the substance.
10. Explain artificial radioactivity with suitable examples.
11. What is radioactive displacement law?
12. Write notes on:
(i) Radioactive equilibrium
(ii) Atomic weight of lead in radioactive minerals
(iii) Tracer technique.
13. Why is natural radioactivity mostly limited among heavier elements?
14. What is a nuclear reaction? Discuss some uses of nuclear reactions.
15. What is nuclear binding energy?
16. What are radio-isotopes? How are they prepared? Mention their uses.
17. Give a comparative account of the nuclear binding energy curve and packing fraction curve.
What informations are available from these curves?
18. Write a short note on nuclear transmutation.
19. What is nuclear fission? Show how nuclear fission is a chain reaction.
20. Write a short note on nuclear fusion.
21. Give a brief account of the nuclear reactors. Derive a relation between mass defect and nuclear
binding energy.
22. Where is the radioactive displacement law invalid?
23. Calculate the amount of energy released during the bombardment of 1 235
0 n on 92 U .
24. Write a short note on radio-carbon dating.
25. Complete the following nuclear reactions:
4 9 4 2 12
6
10
5
Be + He ⎯⎯→ C + ...
24
11
238
92
4
2
24
12
Na ⎯⎯→ Mg + ...
239
90
U ⎯⎯→ Th + ...
1
1
B + He ⎯⎯→ ... + H
7
3
1
1
7
4
Li + H ⎯⎯→ ... + Be.
26. Calculate the time required for 10% disintegration of a sample of thorium. Given the t 1/2
of
thorium = 1.4 × 10 10 yrs.
[Ans. 6.93 × 10 –5 yrs.]
27. Calculate the binding energy in MeV per nucleon of 12 6C .
Given: Mass of H-atom = 1.00782 a.m.u.
Mass of neutron = 1.00866 a.m.u.
Actual mass of C-atom = 12.04
1 amu = 931.4 MeV. [Ans. 54.76 MeV]
28. The half-life of radium is 1590 years. How long will it take for 1 g of the element to lose 0.1 g?
[Ans. 2385 yrs.]