The reaction `A to B` , `DeltaH=+24 kJ//"mole"`. For the reaction `B to C`, `DeltaH=-18 kJ//"mole"`. The decreasing order of enthalpy of `A`, `B`, `C` follow the order

Options

A. A, B, C
B. B, C, A
C. C, B, A
D. C, A, B

Answer

B

Explanation

`A rarr B, Delta H= +24kJ`/mol
`rArr H_(B)- H_(A)= +24`...(i)
`B rarr C, Delta H= -18`kJ/mol
`rArr H_(C) - H_(B)= -18`
`rArr H_(B)- H_(C)= +18` ...(ii)
From Eqs (i) and (ii), we have
`H_(C)- H_(A)= 6`
`therefore H_(B) gt H_(C) gt H_(A)`