A glass vassel after washing contain 54 g of water in it. How much heat must be supplied to evaporate this water? Standard enthalpy of vapourisation of water is 40.79 kJ `mol^-1`.

Boiling point of water at 750mm Hg is 99.63^@C How much sucrose is to be added to 500g of water such that it boils at 100^@C K_b (water)= 0.52K kg mol^(-1)

a) Predict whether entropy increases or decreases in the following changes: i) l_2(S)rightarrowl_2(g) ii) Temperature of a crystalline solid is raised from 0 K and 115 K. iii) Freezing of water b) Calculate the enthalpy of combustion of methane. Given that standard enthalpies of formation of CH_4,CO_2 and H_2O are -75.2, -394 and -285.6 kJ/mol respectively.