Explain the process of controlled and uncontrolled chain reactions.

What is a nuclear reactor? Explain its essential parts with their functions.

' X – rays should not be taken often'. Give the reason.

Identify A, B, C, and D from the following nuclear reactions.
(i) ₁₃AI²⁷ + A  \(\longrightarrow \) ₁₅P³⁰ + B
(ii) ₁₂Mg²⁴ + B  \(\longrightarrow \) ₁₁Na²⁴ + C
(iii) ₉₂U²³⁸ + B \(\longrightarrow \) ₉₃Np²³⁹ + D

₉₂U²³⁵ experiences one \(\alpha\) - decay and one \(\beta\) - decay. Find number of neutrons in the final daughter nucleus that is formed.