'P' is the investment made on an equipment, 'S' is its salvage value and 'n is the life of the equipment in years. The depreciation for rath year by the sum-of years digit method will be
7. The heats of vaporisation of CS2, C2H5OH &H2O are 26.8, 38.6 & 40.6 KJ/kg mole respectively. The order of decreasing inter-molecular forces in these liquids is