Question

$m$ g of a radioactive species (atomic mass $M$) has decay constant $\lambda$. The initial specific activity at zero time is given by :

• A. $\lambda \frac{N_A}{M}$
• B. $\lambda \frac{N_{A}m}{M}$
• C. $\frac{\lambda m}{M}$
• D. $mM{e}^{\lambda }$

Answer 1

The correct option is A $\lambda \frac{N_A}{M}$

The term specific activity is defined as the amount of radioactivity or the decay rate of a particular radionuclide per unit mass of the radionuclide.

$Specificactivity=rateperg$ or $d{s}^{-1}{g}^{-1}$

$=\lambda .\frac{N_A\times m}{M\times m}$

$=\lambda .\frac{N_A}{M}$