The reaction `M_(2)(g) rarrN(g)+(1)/(2)R(g)` shows increase in pressure from 100 mm to 120 mm in 5 minutes. The rate of reaction is ------- mm `min^(-1)`

Options

A. 12
B. 8
C. 4
D. 16

Answer

B

Explanation

`M_(2)(g)rarrN(g)+(1)/(2)R(g)`
`underset(t=5min)(t=0)underset(100-p)(100)underset(P)(0)underset(p//2)(0)`
At the end of `5min`
`P_(Total)=P_(M_(2))+P_(N)+P_(R)`
`=(100-p)+p+p//2=120`
`100+P//2=120`
Thus, `p//2=120-100=20`
`p=40mm`
Reaction rate `=(DeltaP_(M_(2))/(Deltat)=(DeltaP_(N))/(Deltat)=2(DeltaP_(R))/(Deltat)`
`=-((60-100)mm)/(5min)=8mmmin^(-1)`