Question

A heating curve has been plotted for a solid object as shown in the figure. If the mass of the object is $100 \, g$ , then latent heat of vapourisation for the material of the object is [Given, power supplied to the object is constant and equal to $1 \, kW$ ]

• A. $1.5\times 10^{6 \, }J / k g$
• B. $2.5\times 10^{6 \, }J / k g$
• C. $3.5\times 10^{6} \, J / k g$
• D. $9.0\times 10^{6 \, }J / k g$

Answer 1

Answer: (D)

The total heat supplied to the block is
$\displaystyle \int _{1600}^{2500}pdt=mL_{v}$
$1000\times \left(2500 - 1600\right)=0.1L_{v}$
$L_{v}=9.0\times 10^{6}J/kg$