Let weight of A and B be xg. Half-life of A is 1‌min that means it take 1min for compound A to be half of its initial amount. ∴ Weight of A after 1‌min=
x
2
g After 2‌min, it will be =
x
4
g and similarly after 4‌min, weight of A will be
x
16
g Also, half-life of B is 2‌min that means, it take 2 min for compound B to be half of its initial amount. ∴ Weight of B after 2‌min=
x
2
g ∴ Weight of B after 4‌min=
x
4
g ∴ Ratio of compound A and B disintegrated will be =