$A$ rod of length $50 \, cm$ has one end at $25^oC$ and the other end at $125^oC$. The temperature gradient is ....... $^oC/cm$.

What is temperature gradient? When is the temperature gradient considered positive and when is it considered negative?

Write a note on a double-walled flask or a thermos.

$A$ piece of glass is heated to a high temperature and then allowed to cool. If it cracks,a probable reason for this is the following property of glass:

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?

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 $^{\circ} C$)