A slab of stone are 3600 cm2 and thickness 10 cm is exposed on the lower surface to steam at 100∘C. A block of ice of 0∘C rests on upper surface of the slab. In one hour 4.8 kg of ice is melted. The thermal conductivity of the stone in Js−1m−1k−1 is (Latent heat of ice =3.36×105J/kg)