Question

Read the following statements and identify the correct ones:

• A. Radioactive decay obeys the law of exponential decay
• B. Electrons orbiting the nucleus are responsible for radioactivity
• C. Half life period is greater than mean life period
• D. After disintegration radio carbon is converted into N-14

Answer 1

Answer: (A), (D)

The correct options are
A Radioactive decay obeys the law of exponential decay
D After disintegration radio carbon is converted into N-14

A) is true as $\frac{dN}{dt}=-\lambda t$
which on solving gives $N=N_0{e}^{-\lambda t}$ thus, it follows exponential decay.

B) is false as electrons are not responsible for radioactivity rather radioactivity is generally caused due to unstable nuclei.

C) is false as half life is $\frac{0.693}{\lambda }$ and mean life is $\frac{1}{\lambda }$.

D) In radio dating carbon changes to N-14.
${}_6^{14}C{\Rightarrow }_7^{14}N{+}_{-1}^{0}e$