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

Options

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

Answer

A

Explanation

For a first order reaction, `k=(2.303)/(t)log([A]_0)/([A]_t)`
`10^(-2)=(2.303)/(t)log^(20)/(5)implies10^(-2)=(2.303xx0.6020)/(t)implies t=138.6` sec