Question Two $(5p,20$min $)$:

A passive solar house that is losing heat to the outdoors at an average rate of $50,000k\frac{J}{h}$ is maintained at $25C$ at all times during the winter night for $5h.$ The house is to be heated by a number of glass containers each containing $20$ Litters of water at atmospheric pressure, which is heated to $80C$ during the day by absorbing solar energy. The specific heat of water at room temperature is $4\mathrm{.}18k\frac{J}{k}gK.$

$($a$)$ How many bottles are required to keep the house at $25C$ at night for $10$ h $.$

$(3p)$

$($b$)$ How much is the monthly electrical energy saved due to heating the house by glass containers that contains the hot water.

$(1p)$

$($c$)$ How much is the price of the electrical energy saved monthly due to heating the house by the glass containers. The price of electrical energy is $2\mathrm{.}25$ L$.$E$.\frac{?}{kWh}.$

$(1p)$