# After 42 days a 2.0 g sample of phosphorus-32 contains only 0.25 g of the isotope. What is the half-life of phosphorus-32?

##### 2 Answers

May 13, 2018

14 days

#### Explanation:

Mass of atoms initially,

Mass after 42 days,

we have,

if half life is

then

or

May 13, 2018

The half life is

#### Explanation:

The proportion of

This represents

Therefore,

The half life is