Question

The activity of a radioactive nuclide (X${}^{100}$) is $6.023$ curie. If its disintegration constant is

$3.7$ x $10$${}^4$sec${}^{-1}$, then the mass of X is

• A. 10${}^{-23}g$
• B. 10${}^{-15}g$
• C. 10${}^{-16}g$
• D. 10${}^{-14}g$

Answer 1

The correct option is B 10${}^{-15}g$

$\lambda =3.7\times {10}^4{8}^{-1}$

$1curie=3.7\times {10}^{10}$ decays/sec

Activity $R=\lambda N$

$\frac{6.023}{3.7\times {10}^4}\times 3.7\times {10}^{10}=\frac{M}{100}\times 6.023\times {10}^{23}$

${10}^{-15}gm=M$