Heat flows through a long metallic rod from one end to the other under steady-state conditions. The variation of temperature $\theta$ with distance $x$ from the hot end is shown in which of the following graphs?

When two ends of a rod wrapped with cotton are maintained at different temperatures and after some time every point of the rod attains a constant temperature,then

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 ....... $^\circ C/cm$.

Ice starts forming in a lake with water at $0^{\circ}C$ when the atmospheric temperature is $-10^{\circ}C$. If the time taken for $1 \; cm$ of ice to form is $7$ hours,then the time taken for the thickness of ice to change from $1 \; cm$ to $2 \; cm$ is:

Two thin blankets keep more warmth than one blanket of thickness equal to these two. The reason is

What is heat transfer? Write its modes. In which mode,medium is not required?