In a steady state,the temperature at the end $A$ and end $B$ of a $20 \ cm$ long rod $AB$ are $100^{\circ} C$ and $0^{\circ} C$. The temperature of a point,$9 \ cm$ from $A$ is (in $^{\circ} C$)

If a liquid is heated in weightlessness,the heat is transmitted through

Four rods of silver,copper,brass,and wood are of the same shape. They are heated together after wrapping a paper on each. The paper will burn first on:

The difference of temperature in a material can convert heat energy into electrical energy. To harvest the heat energy,the material should have

Assertion: $A$ thermos bottle consists of a double-walled glass vessel with the space between the two walls evacuated, so that the heat transfer between the contents of the bottle and the outside is minimized.
Reason: The vacuum between the two walls inhibits the heat transfer by the radiation mechanism.
Which of the following is correct?

The bottom of a lake is at $0^{\circ} C$ and the atmospheric temperature is $-20^{\circ} C$. If $1 \, cm$ of ice is formed on the surface in $24 \, h$,then the time taken to form the next $1 \, cm$ of ice is ......... $h$.