Three rods of copper, brass and steel are welded together to form $Y$-shaped structure. Area of cross- section of each rod $4 {\mathrm{cm}}^2$. End of copper rod is maintained at $100°\mathrm{C}$ where as ends of brass and steel are kept at $0°\mathrm{C}$. Lengths of the copper, brass and steel rods are $46$, $13$ and $12 \mathrm{cm}$ respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are $0.92$, $0.26$ and $0.12$ CGS units respectively. Rate of heat flow through copper rod is:

A composite block is made of slabs $A$, $B$, $C$, $D$ and $E$ of different thermal conductivities (given in terms of a constant $K$) and sizes (given in terms of length, $L$) as shown in the figure. All slabs are of same width. Heat $Q$ flows only from left to right through the blocks. Then, in steady state:

Two rectangular blocks, having identical dimensions, can be arranged either in configuration $\left(i\right)$ or in configuration $\left(ii\right)$, as shown in the figure. One of the blocks has thermal conductivity $K$ and the other $2K$. The temperature difference between the ends along the $X$ axis is the same in both the configurations. It takes $9 s$ to transport a certain amount of heat from the hot end to the cold end in the configuration $\left(i\right)$. The time to transport the same amount of heat in the configuration $\left(ii\right)$ is: