Question

The $t$${}_{1/2}$ of a radioactive substance is $100sec$. Its decay constant is:

• A. $6.93\times 10$${}^{-3}se{c}^{-1}$
• B. $6.93\times 10$${}^{-2}se{c}^{-1}$
• C. $6.93\times 10$${}^{-1}se{c}^{-1}$
• D. $6.93\times 10$${}^{-4}se{c}^{-1}$

Answer 1

The correct option is A $6.93\times 10$${}^{-3}se{c}^{-1}$

$t_{1/2}=100sec$

$\lambda =\frac{ln2}{t_{1/2}}=\frac{0.693}{100}$$=0.00693{sec}^{-1}$