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

Half life of phosphorous-32 = 14 days

Explanation:

Given data:

Total mass of phosphorous-32 = 2.0 g

After 42 days mass left = 0.25 g

Half life of phosphorous-32 = ?

Solution:

First of all we will calculate the number of half lives passed.

At time zero = 2.0 g

At first half life = 2.0 g/2 = 1.0 g

At 2nd half life = 1.0 g/2 = 0.5 g

At 3rd half life = 0.5 g/2 = 0.25 g

Half life:

Half life = T elapsed / half lives

Half life = 42 days/ 3

Half life = 14 days

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.