Two identical objects A and B are at temperatures ${\mathrm{T}}_{\mathrm{A}}$ and ${\mathrm{T}}_{\mathrm{B}}$ respectively. Both objects are placed in a room with perfectly absorbing walls maintained at temperatures T(${\mathrm{T}}_{\mathrm{A}}$>T>${\mathrm{T}}_{\mathrm{B}}$). The objects A and B attain temperature T eventually. Which one of the following is the correct statement?

(1) ‘A’ only emits radiations while B only absorbs them until both attain temperature

(2) A loses more radiations than it absorbs while B absorbs more radiations than it emits until temperature T is attained

(3) Both A and B only absorb radiations until they attain temperature T

(4) Both A and B only emit radiations until they attain temperature T

When the body has the same temperature as that of surroundings

(1) It does not radiate heat

(2) It radiates the same quantity of heat as it absorbs

(3) It radiates less quantity of heat as it receives from surroundings

(4) It radiates more quantity of heat as it receives heat from surroundings

The spectral energy distribution of star is maximum at twice temperature as that of sun. The total energy radiated by star is 

(1) Twice as that of the sun

(2) Same as that of the sun

(3) Sixteen times as that of the sun

(4) One sixteenth of sun

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

Which of the following statements is true/correct ?

(1) During clear nights, the temperature rises steadily upward near the ground level

(2) Newton's law of cooling, an approximate form of Stefan's law, is valid only for natural convection

(3) The total energy emitted by a black body per unit time per unit area is proportional to the square of its temperature in the Kelvin scale

(4) Two spheres of the same material have radii 1m and 4m and temperatures 4000 K and 2000 K respectively. The energy radiated per second by the first sphere is greater than that radiated per second by the second sphere

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