A substance is kept for 2 hours and three-fourth of that substance disintegrates during this period. The half life of the substance is

Options

A. 2 hr
B. 1 hr
C. 30 min
D. 4 hr

Answer

B

Explanation

Given,
Amount left `N = 1 - (3)/(4) = (1)/(4)`
`N = N_(0) ((1)/(2))^(n) implies ((N)/(N_(0))) = ((1)/(2))^(n)`
`implies ((1)/(4)) = ((1)/(2))^(n)` or `n = 2`
we know `T = n xx t_(1//2) implies t_(1//2) = (2)/(2) = 1 hr`