In a room containing air, heat can go from one place to another:
1. by conduction only
2. by convection only
3. by radiation only
4. by all three modes

A solid at temperature \(T_1\), is kept in an evacuated chamber at temperature \(T_2>T_1\). The rate of increase of temperature of the body is proportional to:
1. \(T_2-T_1\)
2. \(T^2_2 -T^2_1 \)
3. \(T^3_2 -T^3_1\) 
4. \(T^4_2 -T^4_1\)

The thermal radiation emitted by a body is proportional to \(T^n\) where \(T\) is its absolute temperature. The value of \(n\) is exactly \(4\) for:
1. a blackbody
2. all bodies
3. bodies painted black only
4. polished bodies only.

Two bodies \(A\) and \(B\) having equal surface areas are maintained at temperatures \(10^\circ\text C\) and \(20^\circ\text C.\) The thermal radiation emitted in a given time by \(A\) and \(B\) are in the ratio of:
1. \(1 : 1.15\)
2. \(1 : 2\)
3. \(1 : 4\)
4. \(1 : 16\)

One end of a metal rod is kept in a furnace. In steady state, the temperature of the rod

1.  increases

2.  decreases

3.  remains constant

4.  is nonuniform

Newton’s law of cooling is a special case of:
1. Wien’s displacement law
2. Kirchhoff's law
3. Stefan’s law
4. Planck’s law

               
1. \(a\)
2. \(b\)
3. \(c\)
4. \(d\)

A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly

1.   a straight line

2.   a circular arc

3.   a parabola

4.   an ellipse.

A body cools down from \(65^\circ \text{C}\) to \(60^\circ \text{C}\) in \(5\) minutes. It will cool down from \(60^\circ \text{C}\) to \(55^\circ \text{C}\) in:

One end of a metal rod is dipped in boiling water and the other is dipped in melting ice.

Choose the correct option 

1. (a), (b) 

2. (b), (c) 

3. (d) only 

4. (a), (d)