Question

______ yr. If we start with 1.000 g of strontium-90, 0.953 g will remain after 2.00 yr. This means that the half-life of strontium-90 is ________ yr. 28.8 41.6 2.10 1.91 1.45

Answer 1

Answer:

The half-life of strontium-90 is 28.81 years

Explanation:

Step 1: Data given

Mass of strontium 90 = 1.000 grams

After 2 years there remain 0.953 grams

Step 2: Calculate half-life time

k = (-1/t) * ln (Nt/N0)

⇒ with k = rate constant for the decay

⇒ with N0 = the mass of strontium at the start (t=0) = 1.000 grams

⇒ with Nt =  the mass of strontium after time t (2 years) = 0.953 grams

k = (-1/2) * ln(0.953/1)

k = (-1/2) * (-0.0481) = 0.02405 /yr

t1/2 = 0.693/k= 0.693/ 0.02405 = 28.81  years

The half-life of strontium-90 is 28.81 years