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: