$1\mathrm{.}3$ Explain why

$($a$)$ Two bodies at different temperatures $T_1$ and $T_2$ if brought in thermal contact do not necessarily settle to the mean temperature $\frac{T_1+T_2}{2}.$

$($b$)$ The coolant in a chemical or a nuclear plant $($i$.$e$.,$ the liquid used to prevent the different parts of a plant from getting too hot$)$ should have high specific heat.

$($c$)$ Air pressure in a car tyre increases during driving.

$($d$)$ The elimate of a harbour town is more temperate than that of a town in a desert at the same latitude.