The half life of a radioactive material is 12 days. Calculate the decay constant.

Step 1: Identify given values and what to find
Given: t₁/₂ = 12 days
Find: Decay constant λ

Step 2: Write the relationship between half-life and decay constant
Formula: λ = ln(2)/t₁/₂ = 0.693/t₁/₂

Step 3: Substitute and calculate
λ = 0.693/12
λ = 0.05775 day⁻¹

Step 4: The answer is 0.05775 day⁻¹