For a first order reaction

Options

A. `t_(0.75)=4t_(0.5)`
B. `t_(0.75)=2t_(0.5)`
C. `t_(0.75)=3t_(0.5)`
D. `t_(0.75)=1.5t_(0.5)`

Answer

B

Explanation

For a first order reaction, the time required for `75%` of the reaction to complete is twice that required for `50%` of the reaction to complete because `75%` of the reaction `(100%overset(t_(1//2))(rarr)50%overset(t_(1//2))(rarr)25%)`involves two half lives while `50%` of the reaction `(100%overset(t_(1//2))to50%)` involves just one half life.