Question

Radioactive disintegration is a reaction of:

• A. first order
• B. second order
• C. zero order
• D. third order

Answer 1

Answer: (A)

first order

Laws of Radioactive Disintegration

The number of atoms disintegrated per second at any instant is directly proportional to the number of radioactive atoms actually present in the sample at that instant.

If No be the total number of atoms at t = 0, N be the total number of atoms left in the sample at time t then $\frac{-dN}{dt}$ will be the rate of disintegration.

(-ve sign indicates that the number of atoms left undecayed decreases with time).

Hence, it is a first order process.