A first order reaction has specific rate of `10^(-2)s^(-1)`. How much time will it take for 20 g of the reactant to reduce to 5 g?

Options

A. 238.6 second
B. 138.6 second
C. 346.5 second
D. 693.0 second

Answer

B

Explanation

`t_(t//2)=(0.693)/(10^(-2))` second
For the reduction of 20 g of reactant to 5g , two `t_(1//2)` is rquired .
`:. t=2xx(0.693)/(10^(-2))` second
`=138.6` second