The rate of disintegration of a radioactive sample is R and the...

Law of radioactive decay is given as, $\frac{d N}{d t}=-\lambda$N where, $\frac{d N}{d t}=$ rate of disintegration So, $<img src="https://firebasestorage.googleapis.com/v0/b/quantrexacademy-app.firebasestorage.app/o/questions$ \\ R=-\lambda N \Rightarrow $\frac{R}{N}=-\lambda=\text{ constant }$where, $\lambda=$ decay constant So, the graph $\frac{R}{N}$ versus $t$ is as, So, the correct graph shown in option (d).