Question

The half life of a radioactive isotope ‘X’ is 20 years. It decays
to another element ‘Y’ which is stable. The two elements
‘X’ and ‘Y’ were found to be in the ratio of 1 : 7 in a sample
of a the given rock. The age of the rock is estimated to be
(a) 60 years (b) 80 years
(c) 100 years (d) 40 years

Answer 1

Answer:

I thought c option is correct

hope it will help