The rate constant for a first order reaction is `4.606 xx 10^(-3) s^(-1)`. The time required to reduce 2.0g of the reactant to 0.2g is:

Options

A. 200 s
B. 500 s
C. 1000 s
D. 100 s

Answer

B

Explanation

For first reaction:
`k = (2. 303)/( t) log"" ( [R_a])/( [R_1])`
`4.606 xx 10^(-3) = (2. 303)/( t) log"" ([2])/( [0.2])`
`t= (2.303)/( 4.606 xx 10^(-3) ) log 10`
`t = (10^3)/( 2) = 500`s