Select correct statement related to heat …….

A partition wall has two layers $A$ and $B$ in contact, each made of a different material. They have the same thickness but the thermal conductivity of layer $A$ is twice that of layer $B$. If the steady state temperature difference across the wall is $60K$, then the corresponding difference across the layer $A$ is ……. $K$

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 $Image$

$(A)$ heat flow through $A$ and $E$ slabs are same.

$(B)$ heat flow through slab $E$ is maximum.

$(C)$ temperature difference across slab $E$ is smallest.

$(D)$ heat flow through $C =$ heat flow through $B +$ heat flow through $D$.

Six wire each of cross-sectional area $A$ and length $l$ are combined as shown in the  figure. The thermal conductivities of copper and iron are $K_1$ and $K_2$ respectively.  The equivalent thermal resistance between points $A$ and $C$ is :-

Two different rods $A$ and $B$ are kept as shown in figure. The variation of temperature of different cross sections is plotted in a graph shown in figure. The ratio of thermal conductivities of $A$ and $B$ is