From the following data at `25^(@)C`
`{:("Reaction ",Delta_(r) H^(@) kJ//mol),((1)/(2)H_(2)(g) + (1)/(2)O_(2)(g) rarr OH (g),42),(H_(2)(g) + (1)/(2)O_(2)(g) rarr H_(2)O_(g),-242),(H_(2)(g) rarr 2H(g),436),(O_(2)(g) rarr 2O(g),495):}`
Which of the following statement(s) is/are correct:
Statement (a): `Delta_(r)H^(@)` for the reaction `H_(2)O(g) rarr 2H(g) + O(g)`
Statement (b): `Delta_(r)H^(@)` for the reaction `OH(g) rarr H(g) + O(g)` is
Statement (c) : Enthalpy of formation of H(g) is `-218` kJ/mol
Statement (d): Enthalpy of formation of OH(g) is 42 kJ/mol

Options

A. Statement c
B. Statement a, b, c
C. Statement b, c
D. statement a,d

Answer

D

Explanation

(a) `H_(2)O rarr 2H + O`
`Delta H = 2 Delta H_(f_(H)) + Delta H_(f_(0)) - Delta H_(f_(H_(2)O))`
`= 4.36 + (495)/(2) - (-242) = 925.5`
(b) `Delta H rarr H + O`
`Delta H = Delta H_(f_(H)) + Delta H_(f_(O)) - Delta H_(f_(OH))`
`= (436)/(2) + (495)/(2) - 42= 423.5`
(c ) `Delta H_(f) " of" H= (436)/(2) = 218`
(d) `Delta H_(f) " of " OH = 42`