A substance is in the solid form at `0^@`C. The amount of heat added to this substance and its temperature are plotted in the following graph. If the relative specific heat capacity of the solid substance is 0.5, find from the graph (i) the mass of the substance, (ii) the specific latent heat of the melting process and (ii) the specific heat of the substance in the liquid state.
Specific heat capacity of water `=1000 cal//kg//K`

Explanation

1000 cal of heat raises the temperature of the substance from `0^@` C to `80^@` C.
`1000=m(1000xx0.5)xx80`
(`because` specific heat`=`relative sp. Heat`xx`of water)
or `m=0.025kg`
Latent heat `=200xx5=1000cal` (`because` 1 div reads 200cal) `=0.025xxL`
`L=40000 cal//kg`
In the liquid state teperature rises from `80^@`C to `120^@` C, that is by `40^@` C after absorbing 600 cal.
`0.025Sxx40=600` or `S=600cal//kg//K`