1.563 g
Further explanation
Given
A half life of 2.5 days ⇒ t1/2 = 2.5 days
initial sample ⇒ 25 g
duration of decay ⇒ 10 days
Required
sample left after 10 days
Analysis
Use decay Formula :
[tex]\tt Nt=No.\dfrac{1}{2}^{T/t1/2}[/tex]
Solution
[tex]\tt Nt=25.\dfrac{1}{2}^{10/2.5}\\\\Nt=25.\dfrac{1}{2}^4\\\\Nt=\boxed{\bold{1.563~g}}[/tex]
Paraphrase
Substance left after 10 days = 1.563 g
