The decay constant is i 0.1155, and there would be 16 mg left after 24 hours.
The relationship between the half-life, T₀.₅, and the decay constant, λ, is given by
T₀.₅ = 0.693/λ.
Solving for λ, we will multiply both sides by λ first:
(T₀.₅)(λ) = 0.693
Since we know the half life is 6 hours, this gives us:
6λ = 0.693
Dividing by 6, we have
λ = 0.693/6 = 0.1155.
The decay constant will be k in our decay formula, and N₀, the original amount of substance, is 250:
N(24) = 250e^(-0.1155*24) = 15.6 ≈ 16
