Question

Ten grams of 57Co kept in an open container beta-decays with a half-life of 270 days. The weight of the material inside the container after 540 days will be very nearly
(a) 10 g
(b) 5 g
(c) 2.5 g
(d) 1.25 g.

Answer 1

Dear Student,

◆ Answer -

(c) 2.5 g

● Explaination -

Given that half life of Co is 270 days.

In first 270 days, mass of cobalt is halved from 10 g from to 5 g.

In next 270 days, mass of cobalt is halved from 5 g from to 2.5 g.

So in total 540 days, weight of the material inside the container will be 2.5 g.

Thanks dear. Hope this helps you...

Answer 2

Inside the container, the material’s weight after 540 days will be 10 g.

Explanation:

It is known that when beta decay takes place, the electrons will be produced. So, when 57Co undergoes beta decay, there will be a production of electrons. But it is to be noted that the mass of electron is very less, which is $9.11 \times 10^{-31} \mathrm{kg}$ when compared to the Cobalt (Co) atom. So, though the large beta decay of atoms take place after 570 days, the material’s weight in the container will be nearly 10 g.