$30 \mathrm{g}$ ice at $0°\mathrm{C}$ is mixed with $2 \mathrm{g}$ steam at $100°\mathrm{C}$. The final temperature of the mixture is

Three identical conductors, $P, Q$ and $R$ are symmetrically fixed at point $O$ as shown in figure. The temperature of junction $O$ is

Two cylinders of same diameter and length one of iron and other of silver are placed in close contact as shown. If thermal conductivity of silver is $11$ times than that of iron, then temperature of interface A is approximately