Question

The half-life of helium-5 is 7.6 × 10-22 seconds, and the half-life of helium-9 is 7 × 10-21 seconds. Approximately how many times greater is the half-life of helium-9 than that of helium-5?

Answer 1

Explanation:

If 10-22 means 10⁻²², you need to use a ^ to indicate the exponent: 10^(-22)

(7×10⁻²¹)/(7.6×10⁻²²) = (7×10⁻²¹)/(0.76×10⁻²¹) = 7/0.76 ≅ 9.2