Question

If $ \lambda $ is decay constant and $N$ the number of radioactive nuclei of an element, then the decay rate $(R)$ of that element is

• A. $ \lambda N^{2}$
• B. $ \lambda N $
• C. $ \frac{\lambda }{N} $
• D. $\lambda^{2}N $

Answer 1

Answer: (B)

At any instant the rate of decay of radioactive atoms is proportional to the number of atoms present at that instant ie,
$-\frac{d N}{d t} \propto N$
or $-\frac{d N}{d t}=R=\lambda N$
where $\lambda$ is decay constant,