Question

if the half life of substance z is 2.5 years how long will it take for 48 grams of substance z to decay such that only 3 grams remain?

Answer 1

It takes 10 years for the substance z to decay from 48g to 3g

Explanation:

Given:

Half life of z = 2.5 years

Final amount of Z = 3 g

Initial amount of Z = 48 g

According to the question, it takes 2.5 years for substance Z to reduce to half.

So,

In 2.5 years, the amount of z = $\frac{48}{2} = 24g$

In next 2.5 years, the amount of z = $\frac{24}{2} = 12 g$

In next 2.5 years, the amount of z = $\frac{12}{2} = 6g$

In next 2.5 years, the amount of z = $\frac{6}{2} = 3g$

To reduce the amount from 48g to 3g, total years = 2.5 + 2.5 + 2.5 + 2.5

                                                                                   = 10 years

Therefore, it takes 10 years for the substance z to decay from 48g to 3g