For the first order reaction `A(g) rarr 2B(g) + C(g)`, the initial presuure is `P_(A) = 90 m Hg`, the pressure after `10` minutes is found to be `180 mm Hg`. The rate constant of the reaction is

Options

A. `2 xx 10^(-3) sec^(-1)`
B. `2 xx 10^(3) sec^(-1)`
C. `1.15 xx 10^(-3) sec^(-1)`
D. `1.15 xx 10^(3) sec^(-1)`

Answer

C

Explanation

`k=2.303/t log_(10) a/(a-x) = 2.303/(10 xx 60) log_(10) 90/(90-45)`
`therefore` Pressure due to unreacted `x=180/4 = 45` mm Hg `~~ 1.16 xx 10^(-3) sec^(-1)`.