The density of water is maximum at:

1. 39.2 °F

2. 4 °F

3. 0 °C

4. 273 K

A block of ice at -12 °C is slowly heated and converted into steam at 100 °C. Which of the following curves best represents the event?

1.

2.

3.

4.

In engines, water is used as a coolant, because:

1. It is a good conductor of heat energy.

2. It has a low density.

3. It has high specific heat.

4. It is a bad conductor of heat energy.

Select correct statement related to heat.

1. Heat is possessed by a body.

2. Hot water contains more heat as compared to cold water.

3. Heat is energy which flows due to temperature difference.

4. All of these

Which of the following factors affect the thermal conductivity of a rod?

1. Area of cross-section

2. Length of rod

3. Material of rod

4. All of these

What is the dimensional formula for thermal resistance?

1. $\left[{\mathrm{M}}^{-1}{\mathrm{L}}^{-2}{\mathrm{T}}^{-1}\mathrm{K}\right]$

2. $\left[{\mathrm{ML}}^2{\mathrm{T}}^{-2}{\mathrm{K}}^{-1}\right]$

3. $\left[{\mathrm{ML}}^{-3}{\mathrm{T}}^2{\mathrm{K}}^{-1}\right]$

4. $\left[{\mathrm{M}}^{-1}{\mathrm{L}}^{-2}{\mathrm{T}}^3\mathrm{K}\right]$

Two ends of a rod of a non-uniform area of cross-section are maintained at temperatures T₁ and T₂ (T₁>T₂) as shown in the figure.

If l is heat current through the cross-section of conductor at a distance x from its left face, then the variation of l with x is best represented by:

1. 

2. 

3. 

4. 

Four rods of the same material with different radii \(r\) and length \(l\) are used to connect two reservoirs of heat at different temperatures. Which one will conduct maximum heat?
1. \(r=1~\text{cm}, l= 1~\text{m}\)
2. \(r=2~\text{cm}, l= 2~\text{m}\)
3. \(r=1~\text{cm}, l= \frac{1}{2}~\text{m}\)
4. \(r=2~\text{cm}, l= \frac{1}{2}~\text{m}\)

Four rods of the same material and having the same cross-sectional area and length have been joined as shown. The temperature of the junction of four rods will be:

1. 20°C

2. 30°C

3. 45°C

4. 60°C

Why it is hotter for the same distance over the top of a candle than it is inside of its flame?

1. Conduction of heat in the air is upward.

2. Heat is maximum radiated in the upward direction.

3. Radiation and conduction both contribute to transferring heat upwards.

4. Convection takes more heat in the upward direction.