Two gases `N_(2)and H_(2)` are allowed to react from mixture of `N_(2)H_(2)(1) and N_(2)H_(4)(g)` leaving none of the reactants. Formation of `N_(2)H_(2)` (1) does not create any energy change whereas formation of 1 ml `N_(2)H_(4)(g)` absorbs 2 Joule energy. Ratio of volume contraction to energy change (in ml/Joule) during reaction when 30 ml `N_(2)and 40` ml `H_(2)` react under similar conditions of temperature and pressure.

Explanation

`N_(2)+H_(2)toN_(2)H_(2)(1)+N_(2)H_(4)(g)`
`POAC on H " "a ml" "bml`
`30xx2=2a+2bimpliesa+b=30`
`POAC on H40xx2=2a+4bimpliesa+2b=30`
`b=10,a=20`
`V.C.=(30+40)-10=60ml`
Energy change `=10xx2=20`
`(V.C.)/("Energy change")=(60)/(20)=3`