The following data is obtained during the first order thermal decomposition of
`2A(g)rarrB(g)+C(s)` at constant volume and temperature
`{:("S.No.","Time","Total pressure"),(1.,"At the end of 10 minutes",300),(2.,"After completion",200):}`
The rate constant in `"min"^(-1)` is

Options

A. 0.0693
B. 6.93
C. 0.00693
D. 69.3

Answer

A

Explanation

`{:(,2A(g)rarr,B(g)+,C(s)),("Initial",P_(0),0,0),("After time t",P_(0)-2p,p,0):}`
Pressure afrer time t, `p_(t) = P_(0)=P_(0)-2p +p = P_(0)-p`
After concentration `= P_(0)//2`
in `P_(0)=p=300` pascals, `P_(0)//2=200` pascals
`P_(0)=400` pascals, `p = 100` pascals
`k=(2.303)/(t)"log"(P_(0))/(P_(0)-2p)`
`=(2.303)/(10)"log"(400)/(400-200)`
`=(2.303)/(10)xx0.3010 "min"^(-1)=0.0693 "min"^(-1)`.