Question

Which of the following statement (s) is /are true?
A. `DeltaE=0` for combustion of `C_(2)H_(6)(g)` in a sealed rigid adiabatic container
B. `Delta_(r)H^(@)` (S, monoclinic) `ne` 0
C. If dissociation energy of `Ch_(4)(g) ` is 1656 KJ/mol and `C_(2)H_(6)(g)` is 2812 KJ/mol, then value of C-C bond energy will be 328 KJ/mol
D. If `DeltaH_(r)(H_(2)O,g)` =-242 KJ/mol, `DeltaH_("vap")(H_(2)O,l)` =44 KJ/mol then `Delta_(e)H^(@)(OH^(-), aq)` will be -142 KJ/mol

Answer 1

Correct Answer - A::B::C
(A) `DeltaE` will be -ve for combustion reactions
`DeltaH_(f)^(@)` (`S_(1)` rhombic )=0
(C) `CH_(4)(g) rarr C(g) + 4H(g) " " DeltaH=1656 KJ//"mole" =4DeltaH_(C-H)`
`C_(2)H_(6)(g) rarr 2C(g) + 6H(g) " " DeltaH=2812 KJ//"mole"=6 DeltaH_(C-H) + DeltaH_(C-C)`
so `DeltaH_(C-C) = (2812 - (6)/(4) xx 1656) KJ//"mole" = 328KJ//"mole"`
(D) Can not be concluded from given data