A sample of a pure substance of mass 0.15 kg is heated from a solid at its melting point by a heater supplying thermal energy at a constant rate of 80 W. The graph shows how the temperature of the sample varies with time.
What is the specific latent heat of vaporisation, LvL_vLv, of the substance?
8.0×104 J kg−18.0 \times 10^4\text{ J kg}^{-1}8.0×104 J kg−1
1.6×105 J kg−11.6 \times 10^5\text{ J kg}^{-1}1.6×105 J kg−1
2.4×104 J kg−12.4 \times 10^4\text{ J kg}^{-1}2.4×104 J kg−1
3.7×105 J kg−13.7 \times 10^5\text{ J kg}^{-1}3.7×105 J kg−1