Question

Radioactivity of a radioactive element remains $1/10$ of the original radioactivity after $2.303s$. The half life period of radioactive element in second is:

• A. $2.303$
• B. $0.2303$
• C. $0.693$
• D. $0.0693$

Answer 1

Answer: (C)

$0.693$

$\lambda =\frac{2.303}{t}{\log }_{10}\frac{a}{(a-x)}$
or $\lambda =\frac{2.303}{2.303}{\log }_{10}\frac{1}{1/10}=1$

$T=\frac{0.693}{\lambda }=0.693$