(Note: Specific heat of the metal $=500 \,J / kg /{ }^{\circ} C$; Heat transfer coefficient from block to air $=50 \,W / m ^2 /{ }^{\circ} C$ )
Taking the thermal conductivity of Ice as ${K}$, and its specific latent heat of fusion as $L$, the rate of Increase of the thickness of ice layer, at this instant would be given by