Answer:
It will take 8 hours for the element to decay
Step-by-step explanation:
Half life: This is the time taken for half the total number of atoms in a given sample of a radioactive element to decay.
λ/λ₁ = 2(ᵃ/ⁿ)......................... Equation 1
λ₁ = radioactive remain, λ = original amount, a = total disintegration time, n = half life.
Given: λ = 100%, λ₁= 100-93.75 = 6.25%, n = 2 hours.
Substituting these values into equation 1,
100/6.25 = 2(ᵃ/²)
16 = 2(ᵃ/²)
2⁴ = 2(ᵃ/²)
Equating the base from both side of the equation,
4 = a/2
a = 4×2
a = 8 hours.
Thus it will take 8 hours for the element to decay