`A(g)overset(Delta)rarrP(g)+Q(g)+R(g),` follows first order kinetics with a half-life of 69.3 s at `500^(@)C.` Starting from the gas A enclosed in a container at `500^(@)C` and at a pressure of 0.4 atm, the total pressure of the system after 230 s will be

Explanation

`A(g)overset(Delta)toP(g)+Q(g)+R(g)`
`{:("At "t=0",",,0.4" atm",,,0,,0,,0,,,),("After 230 s,",,0.4-p,,,p,,p,,p",",,,"Total "(P_(t))=0.4-p+3p=0.4+2p):}`
or `p=(p_(t)-0.4)/(2)`
After 230 s, `P_(A)=0.4-p=0.4-(P_(t)-0.4)/(2)=(0.8-p_(t)+0.4)/(2)=(1.2-p_(t))/(2)`
As reaction is of 1st order
or ` k=(2.303)/(t)log""(P_(0))/(P_(A))`
`(0.693)/(t_(1//2))=(2.303)/(230)log""(0.4)/((1.2-p_(t))//2)=(2.303)/(230)log""(0.8)/(1.2-p_(t))`
`(0.693)/(69.3)=(2.303)/(230)log""(0.8)/(1.2-p_(t))" or "log""(0.8)/(1.2-p_(t))=(0.693)/(69.3)xx(230)/(2.303)=0.9987`
`:.(0.8)/(1.2-p_(t))="antilog "0.9987~=10" or "12-10" p"_(t)=0.8" or "p_(t)=1.12" atm"`