The half-life of strontium - 90 is approximately 29 Year's. How much of a 150 g sample of strontium-90 will remain after 116 years

The half-life is 29 years.

116 : 29 = 4

So we will have 4 periods of half-life:

(1/2) ^4 = 1/16

150 g * 1/16 = 9.375 g

Answer:

9.375 g of strontium - 90 will remain after 116 years.