A liquid in a beaker has temperature $\theta \left( t \right)$ at time $t$ and ${\theta _0}$ is temperature of surroundings, then according to Newton's law of cooling the correct graph between loge ${\log _e}(\theta  – {\theta _0})$ and $t$ is

Which of the following cylindrical rods will coduct most heat when their ends are maintained at the same steady temperatures?

Six identical conducting rods are joined as shown in figure. Points $A$ and $D$ are maintained at temperatures $200\,^oC$ and $20\,^oC$, respectively. the temperature of junction $B$ will be……… $^oC$

Two rods of same material have same length and area. The heat $\Delta Q$ flows through them for $12\, minutes$ when they are jointed in series. If now both the rods are joined in parallel, then the same amount of heat $\Delta Q$ will flow in …….. $\min$.

Hot water cools from $60\,^oC$ to $50\,^oC$ in the first $10\, min$ and to $42\,^oC$ in the next $10\, min$. The temperature of the surrounding is ……… $^oC$