For cooking the food, which of the following type of utensil is most suitable

The two ends of a rod of length $L$ and a uniform cross-sectional area $A$ are kept at two temperatures $T_1$ and $T_2 (T_1 > T_2)$. The rate of heat transfer,$\frac{ dQ }{dt}$, through the rod in a steady state is given by

Which of the following circular rods. (given radius $ r$ and length $l$ ) each made of the same material as whose ends are maintained at the same temperature will conduct most heat

There is formation of layer of snow $x\,cm$ thick on water, when the temperature of air is $ – {\theta ^o}C$ (less than freezing point). The thickness of layer increases from $x$ to $y$ in the time $t$, then the value of $t$is given by

One end of a metal rod of length $1.0 m$ and area of cross section $100c{m^2}$ is maintained at ${100^o}C.$If the other end of the rod is maintained at ${0^o}C$, the quantity of heat transmitted through the rod per minute is (Coefficient of thermal conductivity of material of rod =$100W/m-K$)