Question

The activity of a radioactive nuclide (X¹⁰⁰) is 6.023 Curie. If its disintegration constant is 3.7 x 10⁴ sec^-1. The mass of X after t sec is

(a) 10^-3 g

(b) 10^-6 g

(c) 10^-14 g

(d) 10^-15 g

Answer 1

Correct option is (d) 10^-15 g

λ = 3.7 × 10⁴ sec⁻¹  

1 curie = 3.7 × 10¹⁰ decays/sec

Activity R = λN

\(\frac{6.023}{3.7 \times 10^4} \times 3.7 \times 10^{10} = \frac M{1000} \times 6.023 \times 10^{23}\)

\(M = 10^{-15}gm\)