Starting with a sample of pure `.^(66)Cu, 7//8` of it decays into `Zn` in `15` minute. The corresponding half-life is:

Options

A. 5min
B. `7 (1)/(2)` min
C. 10 min
D. 15 min

Answer

A

Explanation

Part of sample remaining `= (1- (7)/(8)) N_(0)= (1)/(8) N_(0)`
Now, `(N)/(N_(0)) = ((1)/(2))^((t)/(T_(1//2)))`
`rArr (1)/(8) = ((1)/(2))^((15)/(T_(1//2))) rArr 3= (15)/(T_(1//2)) rArr T_(1//2)= 5` min
`rArr T_(1//2)=5` min