What is SMOG?

Literally,  smoke + fog= smog.
Smoke is the collection of unburnt fuel particles suspended in the air.
Fog is the suspended water particles in the air.
The combination of these suspended particles gives the smog.

Why do cooking vessels have thick bases?

theloveforphysics

Cooking vessel is provided with thick base to increase the mass so that its heat capacity increases and the base can absorb more heat and impart it to the food so that food is cooked quickly and the base remains hot for longer period of time

theloveforphysics

Temperature doesn't change during phase change( melting, boiling etc..). Why?

The heat added to the solid is absorbed by the particles and it is utilised in overcoming the intermolecular force of attraction between the particles. So heat absorbed in solids is changed to potential energy without any change in kinetic energy of the molecules. As temperature in Kelvin scale is the measure of kinetic energy of particles, there is no change in temperature during melting.

Temperature of surrounding falls after a heavy shower. Why?

Water has high specific heat capacity . It absorbs large amount of heat from the surrounding without  much rise in its temperature .Hence the temperature falls .

CALORIMETER

It is a device to measure the heat lost or gained by one substance mixed with another at different temperature.
It is based on the principle of mixtures or principle of calorimetry.
Calorimeter is made of thin sheet of copper kept in a wooden jacket to with other insulating materials so that the process exchange heat by conduction is checked. Its surfaces are polished to check the process of radiation. Wooden or asbestos lid is used to minimise the loss of heat by convection.

Thin sheet is used to lower the heat capacity.

Temperature falls as altitude increases, Why?

The volume of rising warm air increases with height due the availability of more space above. This expansion (Joule-Thompson effect) results in cooling effect. Hence hillstations have low temperature. This phenomena helps in the formation of clouds and various forms of precipitation.