The silvered surface in a vacuum flask reduces heat loos due to

How long will it take to heat 3kg of water from 28^oC to 88^oC in an electric kettle taking 6a from a 220V supply? [specific heat capacity of water = 4180 J kg^-1K^-1]

The amount of energy required to change a kilogram of ice in water without a change in temperature is

A quantity of steam at 100^oC condenses to water at the same temperature by releasing 6.9 x 10⁴J of energy. Calculate the mass of the condensed steam. [specific latent heat of vaporization of eater = 2.3 x 10⁶ J kg^-1]

The temperature of a liquid falls after some of it has evaporated because