Consider the following process for the conversion of A to D.

How many of the following represent the CORRECT expressions, according to the Hess's law?
i. `DeltaH_(1)+DeltaH_(2)+DeltaH_(3)=DeltaH_(4)+DeltaH_(5)`
(ii) `DeltaH_(6)=DeltaH_(4)+DeltaH_(5)`
(iii) `DeltaH_(3)=DeltaH_(6)-DeltaH_(1)-DeltaH_(2)`
(iv) `DeltaH_(2)=DeltaH_(6)-DeltaH_(4)-DeltaH_(5)`
v. `DeltaH(6)=DeltaH_(1)+DeltaH_(2)+DeltaH_(3)`
(vi) `DeltaH_(4)=DeltaH_(6)+DeltaH_(5)`

Answer

`4`

Explanation

We know that according to the Hess.s law
`DeltaH_("net")=sumDeltaH_(r)`
Since along A to D `DeltaH_(6)` is the enthalpy change it can be writen as
`DeltaH_(6)=DeltaH_(1)+DeltaH_(2)+DeltaH_(3)` and
`DeltaH_(6)=DeltaH_(4)+DeltaH_(5)`
and the above two expressions are equal to each other.
Thus the expressions i,ii,iii and v correctly represent the Hess.s law.