`H_(2)(g) +(1)/(2)O_(2)(g) rarr H_(2)O(l)`
`BE (H-H) = x_(1), BE (O=O)=x_(2)`
`BE(O-H)=x_(3)`
Latent heat of vaporisation of water liquid into water vapour `=x_(4)`, then `Delta_(f)H` (heat of formation of liquid water) is

Options

A. (a) `x_(1) +(x_(2))/(2) -x_(3) +x_(4)`
B. (b) `2x_(3)-x_(1) -(x_(2))/(2)-x_(4)`
C. (c) `x_(1)+(x_(2))/(2)-2x_(3)-x_(4)`
D. (d) `x_(1)+(x_(2))/(2)-2x_(3)+x_(4)`

Explanation

To calculate the heat of formation (ΔH_f) of liquid water from the given reaction:

\[ H_2(g) + \frac{1}{2}O_2(g) \rightarrow H_2O(l) \]

we will use the bond energies provided and the latent heat of vaporization.

### Step-by-Step Solution:

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