Question

Ten grams of $C{o}^{57}$ kept in open container beta-decays with half life of 270 days. The weight of the material in container after 540 days will be very nearly.

• A. 10 gm
• B. 5 gm
• C. 2.5 gm
• D. 1.25 gm

Answer 1

The correct option is A 10 gm

${}^{57}{C}_0$ undergoing beta decay . i.e electron is being produced. But an electron has very less mass as compared to the $C0-atom$ Therefore after $570$ days even through the atom undergo large beta decay, the weight of the material in the container will be nearly $10g$.

Hence, the option $A$ is the correct answer.