A solid material is supplied with heat at a constant rate. The temperature of the material is changing with the heat input as shown in the graph in figure. Study the graph carefully and answer the following questions:

(i) What do the horizontal regions AB and CD represent?
If CD is equal to 2AB, what do you infer?
What does the slope of DE represents?
The slope of OAgtthe slope of BC. What does this indicate?

Explanation

(i) In horizontal portiona AB and CD, temperature remains same hence these portions show change of state.
AB:conservation from solid to liquid state.
CD:convertion from liquid to vapours.
(ii) When change of state takes place, `DeltaQ = mL`
Length of line `alpha` Latent heat
CD=2AB `rArr DeltaQ_(CD)` = `2DeltaQ_(AB)`
`mL_(v)=2mL_(i)rArr L_(V) = 2L_(l)`
Where `L_(l)` and `L_(V)` are the lateent heat of fusion and vaporisation respectively.
(iii) Heat `DeltaQ=mcDeltaT`
`(DeltaT)/(DeltaQ)`=Slope of inclined line
=1/(mc) = 1/(thermal capacity)
The slope of line DE represents reciprocal of heat capacity (iv) Slope of OAgtslope of BC
`(1/(mc)_(s) gt(1/(mc)_(t)rArrc_(l)gtc_(s))`
The specific heat of liquid is greater than that of specific heat of solid.