Question

The rate of disintegration of a radioactive sample is $R$ and the number of atoms present at any time $t$ is $N$ . When $\frac{R}{N}$ is taken alone Y-axis and $t$ is taken alone X-axis, the correct graph is

• A.
• B.
• C.
• D.

Answer 1

Answer: (D)

Law of radioactive decay is given as.
$\frac{dN}{dt}=-\lambda N$
where, $\frac{dN}{dt}=$
rate of disintegration
So, $R=-\lambda N$
$\Rightarrow \frac{R}{N}=-\lambda =$ constant
where, $\lambda =$ decay constant
So, the graph $\frac{R}{N}$ versus $t$ is as,