Study of diborane - class-XI

Boron can undergo the following reactions with the given enthaly changes:
Assume no other reactions are occurring. If in a container (operating at constant pressure) which is isolated from the surrounding, mixture of are passed over excess of B(s), then calculate the molar ratio so that temperature of the container do not change :
${\text{2B}}\left( {\text{s}} \right){\text{ + }}\dfrac{{\text{3}}}{{\text{2}}}{{\text{O}} _{\text{2}}}\left( {\text{g}} \right) \to {{\text{B}} _{\text{2}}}{{\text{O}} _{\text{3}}}\left( {\text{s}} \right);;\Delta H =  - 1260;KJ$
${\text{2B}}\left( {\text{s}} \right){\text{ + 3}}{{\text{H}} _{\text{2}}}\left( {\text{g}} \right) \to {{\text{B}} _2}{H _6}\left( g \right);;\Delta H = 30KJ$