Question

Find the missing value for the radioactive isotope.

a) Half-life
b) Decay constant
c) Initial quantity
d) Final quantity

Answer 1

To calculate the half-life of iodine-131, we use the provided decay constant (λ = 0.138 d⁻¹) with the formula t₁₂ = 0.693 / λ, and find that the half-life is approximately 5.021 years.

Step-by-step explanation:

The question pertains to the concept of radioactive decay and specifically asks for the half-life of the radioactive isotope iodine-131 given its decay constant (λ). To find the half-life from the decay constant, we use the formula t₁₂ = 0.693 / λ. Substituting the given decay constant of iodine-131 (λ = 0.138 d⁻¹) into the formula, we get:

t₁₂ = 0.693 / 0.138 d⁻¹

t₁₂ = 5.021 years (rounded to three significant figures)

Thus, the half-life for iodine-131 is approximately 5.021 years.