When one mole of A is reacted completely in an ice calorimeter at $0° \mathrm{C}$ and 1 atm, it is found that the volume of equilibrium mixture of ice and water decreased by 0.25 mL. The .${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{H}}_{273}$ for the reaction
$2\mathrm{A}⟶\mathrm{B}+2\mathrm{C}$
is: (the densities of water and ice at 0° and 1 atm are 1.00 and $0.96 \mathrm{gm}/{\mathrm{cm}}^3$ , respectively and latent heat of fusion of ice at 0° C and 1 atm is 80 cal/gm)
 [Use : 1 if .${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{H}}_{273}$ is +ve and 2 if .${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{H}}_{273}$ is -ve and answer as 1 abc or 2 abc, where abc is magnitude of ${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{H}}_{273}$]