If 25/26 quantity of a ratioactive element disintegrates in two hours, its half life would be

Options

A. 1 hour
B. 45 minutes
C. 30 minutes
D. 15 minutes

Answer

C

Explanation

Quantity of radioactive element decaued `=(15)/(16)`
Quantity left `=1-(15)/(16)=(1)/(16)`
`therefore (1)/(16)=1xx((1)/(2))^(n)` or `((1)/(2))^(n)=((1)/(2))^(n)`
`therefore n=4`
Thus in two hours four half lives elapse.
`therefore` One half life `=(2xx60)/(4)=30` minutes.