Correct Answer - A
Heat is lost by steam in two stages (i) for charge of state from steam at `100^(@)C` to water at `100^(@)C` is `mxx540` (ii) to change water at `100^(@)C` to water at `80^(@)C` is `m xx 1 xx (100-80)`, where `m` is the mass of steam condensed.
Total heat lost by steam = `m xx 540+mxx20=560m cal`
Heat gained by calorimeter and its contents
`=(1.1 + 0.2) xx (80-15) = 1.12 xx 65 cal`
Using principle of calorimetry,
Heat gained = heat lost
`:. 560 m = 1.12 xx 65`
`m = 0.130 gm`.