A cup of coffee cools from $90^{\circ} \mathrm{C}$ to $80^{\circ} \mathrm{C}$ in $\mathrm{t}$ minutes, when the room temperature is $20^{\circ} \mathrm{C}$. The time taken by a similar cup of coffee to cool from $80^{\circ} \mathrm{C}$ to $60^{\circ} \mathrm{C}$ at a room temperature same at $20^{\circ} \mathrm{C}$ is :

A body cools from $60^{\circ} C$ to $40^{\circ} C$ in $6$ minutes. If, temperature of surroundings is $10^{\circ} C$. Then, after the next 6 minutes, its temperature will be $………{ }^{\circ} C$.

A cubic metal block of mass $5 \,kg$ and edge length $0.1 \,m$ and at an initial temperature of $100^{\circ} C$ is placed on a thermally insulating flat surface and exposed to air at $0^{\circ} C$. The time in seconds required to cool the block to a temperature of $37^{\circ} C$ is closest to

(Note: Specific heat of the metal $=500 \,J / kg /{ }^{\circ} C$; Heat transfer coefficient from block to air $=50 \,W / m ^2 /{ }^{\circ} C$ )

A beaker full of hot water is kept in a room. If it cools from $80^{\circ} C$ to $75^{\circ} C$ in $t_1$, minutes, from $75^{\circ} C$ to $70^{\circ} C$ in $t_2$ minutes and from $70^{\circ} C$ to $65^{\circ} C$ in $t_3$ minutes, then

The temperature of a body falls from $62^oC\, to\, 50^oC$ in $10$ minutes. If the temperature of the surroundings is $26^oC$, the temperature in next $10$ minutes will become  …… $^oC$