If `DeltaH` is the change in enthylpy and `DeltaU`, the change in internal energy accompanying a gaseous reactant then

Options

A. `DeltaH` is always greater than `DeltaU`
B. `DeltaH lt DeltaU` only if the number of moles of the products is greater than the number of moles of the reactants
C. `DeltaH` is always less than `DeltaU`
D. `DeltaH lt DeltaU` only if the number of moles of products is less than the number of moles of the reactants.

Answer

D

Explanation

`DeltaH=DeltaU+PDeltaV`
`=DeltaU+(Deltan_(g))RT`.
If `n_(P) lt n_(R),Deltan_(g)=n_(p)-n_(r)=-ve` ,brgt Hence, `DeltaH lt DeltaU`