$A$ body cools from $80^{\circ} C$ to $60^{\circ} C$ in $5$ minutes. The temperature of the surrounding is $20^{\circ} C$. The time it takes to cool from $60^{\circ} C$ to $40^{\circ} C$ is........... $s$

If a metallic sphere cools from $62^{\circ}C$ to $50^{\circ}C$ in $10 \; \text{minutes}$ and in the next $10 \; \text{minutes}$ cools to $42^{\circ}C$,then the temperature of the surroundings is ......... $^{\circ}C$.

Discuss the experiment verifying Newton's law of cooling.

$A$ liquid is filled in a vessel which is kept in a room with a temperature of $20^{\circ}C$. When the temperature of the liquid is $80^{\circ}C$,it loses heat at the rate of $60 \; cal/sec$. What will be the rate of loss of heat when the temperature of the liquid is $40^{\circ}C$ in $cal/sec$?

$A$ pan filled with hot food cools from $94^{\circ}C$ to $86^{\circ}C$ in $2$ minutes. When the room temperature is $20^{\circ}C$, how long will it take to cool from $74^{\circ}C$ to $66^{\circ}C$?

In an experiment to verify Newton's law of cooling,a graph is plotted between the temperature difference $(\Delta T)$ of the water and surroundings and time as shown in the figure. The initial temperature of water is taken as $80^{\circ}C$. The value of $t_{2}$ as mentioned in the graph will be...........