A body cools down from \(80^{\circ}\mathrm{C}\) $\mathrm{to}$ \(70^{\circ}\mathrm{C}\) in 5 minutes. The temperature of the same body will fall from \(70^{\circ}\mathrm{C}\)$\mathrm{}$ $\mathrm{to}$ \(60^{\circ}\mathrm{C}\)$\mathrm{}$ in:

Hot water cools from 60$°\mathrm{C}$ to 50$°\mathrm{C}$ in first 10 minutes and from 50$°\mathrm{C}$ to 42$°\mathrm{C}$ in next 10 minutes. The temperature of surrounding is :

1.  $5°<mspace\; width="1em"></mspace>\mathrm{C}<mspace\; width="1em"></mspace>$

2.  $10°<mspace\; width="1em"></mspace>\mathrm{C}<mspace\; width="1em"></mspace>$

3.  $15°<mspace\; width="1em"></mspace>\mathrm{C}<mspace\; width="1em"></mspace><mspace\; width="1em"></mspace>$

4.  $20°\mathrm{C}$

A body cools from a temperature 3T to 2T in10 minutes. The room temperature is T. Assume that Newton's law of cooling is applicable. The temperature of the body at the end of next 10 minutes will be:
1. \(\frac{7}{4}T\)
2. \(\frac{3}{2}T\)
3. \(\frac{4}{3}T\)
4. \(T\)

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: 

A bucket full of hot water cools from 75$°\mathrm{C}$ to 70$°\mathrm{C}$ in time ${\mathrm{T}}_1$, from 70$°\mathrm{C}$ to 65$°\mathrm{C}$ in time ${\mathrm{T}}_2$  and from 65$°\mathrm{C}$ to 60$°\mathrm{C}$ in time ${\mathrm{T}}_3$, then 
(1) ${\mathrm{T}}_1={\mathrm{T}}_2={\mathrm{T}}_3$              

(2) ${\mathrm{T}}_1>{\mathrm{T}}_2>{\mathrm{T}}_3$

(3) ${\mathrm{T}}_1<{\mathrm{T}}_2<{\mathrm{T}}_3$               

(4) ${\mathrm{T}}_1>{\mathrm{T}}_2<{\mathrm{T}}_3$

Consider two hot bodies, ${\mathrm{B}}_1$ and ${\mathrm{B}}_2$ which have temperatures of \(100^{\circ}\mathrm{C}\)$\mathrm{}$ and \(80^{\circ}\mathrm{C}\)$\mathrm{}$ respectively at \(t=0.\) The temperature of the surroundings is \(40^{\circ}\mathrm{C}\)$\mathrm{}$. The ratio of the respective rates of cooling ${\mathrm{R}}_1$ and ${\mathrm{R}}_2$ of these two bodies at \(t=0\) will be:
1. ${\mathrm{R}}_1:{\mathrm{R}}_2=3:2$
2. ${\mathrm{R}}_1:{\mathrm{R}}_2=5:4$
3. ${\mathrm{R}}_1:{\mathrm{R}}_2=2:3$
4. ${\mathrm{R}}_1:{\mathrm{R}}_2=4:5$

Newton's law of cooling is a special case of
(1) Stefan's law           

(2) Kirchhoff's law

(3) Wien's law             

(4) Planck's law

In Newton's experiment of cooling, the water equivalent of two similar calorimeters is 10 gm each. They are filled with 350 gm of water and 300 gm of a liquid (equal volumes) separately. The time taken by water and liquid to cool from 70°C to 60°C is 3 min and 95 sec respectively. The specific heat of the liquid will be
(1) 0.3 Cal/gm $\times$°C                       

(2) 0.5 Cal/gm $\times$°C

(3) 0.6 Cal/gm $\times$°C                       

(4) 0.8 Cal/gm $\times$°C

The rates of cooling of two different liquids put in exactly similar calorimeters and kept in identical surroundings are the same if 

(1) The masses of the liquids are equal

(2) Equal masses of the liquids at the same temperature are taken

(3) Different volumes of the liquids at the same temperature are taken

(4) Equal volumes of the liquids at the same temperature are taken

The temperature of a liquid drops from 365 K to 361 K in 2 minutes. Find the time during which temperature of the liquid drops from 344 K to 342 K . Temperature of room is 293 K
(a) 84 sec                        (b) 72 sec
(c) 66 sec                        (d) 60 sec