Heat is required to change 1 kg of ice at `-20^@C` into steam. `Q_1` is the heat needed to warm the ice from `-20^@C` to `0^@C`, `Q_2` is the heat needed to melt the ice, `Q_3` is the heat needed to warm the water from `0^@C` to `100^@C` and `Q_4` is the heat needed to vapourize the water. Then

Options

A. `Q_4gtQ_3gtQ_2gtQ_1`
B. `Q_4gtQ_3gtQ_1gtQ_2`
C. `Q_4gtQ_2gtQ_3gtQ_1`
D. `Q_4gtQ_2gtQ_1gtQ_3`

Answer

A

Explanation

`Q_4=mL_W=540cal`
`Q_3=ms_W(100-0)=100cal`
`Q_2=mL_("ice")=80cal`
`Q_1=ms_("ice")(20-0)=20cal`
`Q_(4) lt Q_(3) lt Q_(2) lt Q_(1)`