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 $^{\circ} C$)

$Assertion :$ Woolen clothes keep the body warm in winter.
$Reason :$ Air is a bad conductor of heat.

What is thermal steady state?

Heat is flowing through a conductor of length $l$ from $x = 0$ to $x = l$. If its thermal resistance per unit length is uniform,which of the following graphs correctly represents the variation of temperature $T$ with distance $x$?

If it takes $7 \, h$ to form a $1 \, cm$ thick layer of ice on a pond at $0^o C$,how many hours will it take for the thickness of the ice layer to increase from $1 \, cm$ to $2 \, cm$?

Heat flows through a rod of length $50 \ cm$ and cross-sectional area $5 \ cm^{2}$. Its ends are maintained at $25 \ ^\circ C$ and $125 \ ^\circ C$ respectively. The thermal conductivity of the material of the rod is $0.092 \ kcal/m \cdot s \cdot ^\circ C$. The temperature gradient of the rod is ....... $^\circ C/cm$.