Gulab Jamuns (assumed to be spherical) are to be heated in an oven. They are available in two sizes, one twice bigger (in radius) than the other. Pizzas (assumed to be discs) are also to be heated in the oven. They are also in two sizes, one twice bigger (in radius) than the other. All four are put together to be heated to oven temperature.

(a) Both size gulab jamuns will get heated in the same time.

(b) Smaller gulab jamuns are heated before bigger ones.

(c) Smaller pizzas are heated before bigger ones.

(d) Bigger pizzas are heated before smaller ones.

Choose the correct alterative/s:

1.  (b, c)

2.  (a, d)

3.  (b, d)

4.  (c, d)

Refer to the plot of temperature versus time (figure) showing the changes in the state of ice on heating (not to scale).

(a) The region AB represents the ice and water in thermal equilibrium.

(b) At B, the water starts boiling.

(c) At C, all the water gets converted into steam.

(d) C to D represents water and steam in equilibrium at boiling point.

Choose the correct alterative/s:

1.  (b, c)

2.  (a, d)

3.  (c, d)

4.  (b, d)

A glass full of hot milk is poured on the table. It begins to cool gradually.

(a) The rate of cooling is constant till milk attains the temperature of the surrounding.

(b) The temperature of milk falls off exponentially with time.

(c) While cooling, there is a flow of heat from milk to the surroundings as well as from the surroundings to the milk but the net flow of heat is from milk to the surroundings and that is why it cools.

(d) All three phenomena, conduction, convection and radiation are responsible for the loss of heat from milk to the surroundings.

Choose the correct alterative/s:

1.  (a, b, c)

2.  (a, d)

3.  (b, c, d)

4.  (a, c, d)

A sphere, a cube and a thin circular plate, all of the same material and same mass are initially heated to the same high temperature.

1. Plate will cool fastest and cube the slowest

2. Sphere will cool fastest and cube the slowest

3. Plate will cool fastest and sphere the slowest

4. Cube will cool fastest and plate the slowest

The radius of a metal sphere at room temperature T is R and the coefficient of linear expansion of the metal is $\alpha$. The sphere heated a little by a temperature $∆$T so that its new temperature is T+$∆$T. The increase in the volume of the sphere is approximately:

1. $2\mathrm{\pi R\alpha }∆\mathrm{T}$

2. ${\mathrm{\pi R}}^2\mathrm{\alpha }∆\mathrm{T}$

3. $4{\mathrm{\pi R}}^3\mathrm{\alpha }∆\mathrm{T}/3$

4. $4{\mathrm{\pi R}}^3\mathrm{\alpha }∆\mathrm{T}$

Heat is associated with:

1. kinetic energy of random motion of molecules

2. kinetic energy of orderly motion of molecules

3. total kinetic energy of random and orderly motion of molecules

4. kinetic energy of random motion in some cases and kinetic energy of orderly motion in other

An aluminium sphere is dipped into the water. Which of the following is true?

1. Buoyancy will be less in water at 0°C than that in water at 4°C

2. Buoyancy will be more in water at 0°C than that in water at 4°C

3. Buoyancy in water at 0°C will be the same as that in water at 4°C

4. Buoyancy may be more or less in water at 4°C depending on the radius of the sphere

The graph between two temperature scales A and B is shown in the figure. Between upper fixed and lower fixed points, there are 150 equal divisions on scale A and 100 on scale B. The relationship for conversion between the two scales is given by 

1. $\frac{t_A-180}{100}=\frac{t_B}{150}$

2. $\frac{t_A-30}{150}=\frac{t_B}{100}$

3. $\frac{t_B-180}{150}=\frac{t_A}{100}$

4. $\frac{t_B-40}{100}=\frac{t_A}{180}$

A uniform metallic rod rotates about its perpendicular bisector with the constant angular speed. If it is heated uniformly to raise its temperature slightly,

1. its speed of rotation increases

2. its speed of rotation decreases

3. its speed of rotation remains the same

4. its speed increases because its moment of inertia increases