The temperature of a body falls from \(50^{\circ}\text{C}\)$\mathrm{}$ to \(40^{\circ}\text{C}\)$\mathrm{}$ in \(10\) minutes. If the temperature of the surroundings is \(20^{\circ}\text{C},\)$\mathrm{<mspace\; width="1em"></mspace>t}$hen the temperature of the body after another \(10\) minutes will be:
1. \(36.6^{\circ}\text{C}\)          
2. \(33.3^{\circ}\text{C}\)$\mathrm{}$
3. \(35^{\circ}\text{C}\)             
4. \(30^{\circ}\text{C}\)$\mathrm{}$

A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents. Which of the following curves correctly represents the rate of cooling?

1.		2.
3.		4.

A certain quantity of water cools from \(70^{\circ}\mathrm{C}\) to \(60^{\circ}\mathrm{C}\) in the first 5 minutes and to \(54^{\circ}\mathrm{C}\) in the next 5 minutes. 
The temperature of the surroundings will be: 

Hot coffee in a mug cools from \(90^{\circ}\text{C}\) to \(70^{\circ}\text{C}\) in \(4.8\) minutes. The room temperature is \(20^{\circ}\text{C}.\) Applying Newton's law of cooling, the time needed to cool it further by \(10^{\circ}\text{C}\) should be nearly: