Question

A sample of ${}_{19}^{40}K$ contains invariably ${}_{18}^{40}Ar$. This is because ${}_{19}^{40}K$ has tendency to undergo:

• A. $\alpha$-decay
• B. Positronium decay
• C. $\beta$-decay
• D. $\gamma$-decay

Answer 1

The correct option is B Positronium decay

${}_{19}^{40}K{-}_1^{0}e{\to }_{18}^{40}K$

Positron is $e^{+}$. Therefore, $_{19}^{40} has tendency to undergo positronium decay.