An aluminium block of mass \(2.5\) kg is supplied with \(9000\) J of thermal energy. This causes its temperature to rise by \(4\) K. Which expression gives the specific heat capacity of this aluminium, from this data?
(assume that the block remains solid throughout and that no additional energy is exchanged between the block and the surroundings)
1. \(9000\times2.5\times4\) J kg–1 K–1
2. \(\dfrac{2.5\times4}{9000}\) J kg–1 K–1
3. \(\dfrac{9000\times2.5}{4}\) J kg–1 K–1
4. \(\dfrac{9000}{ 2.5 \times4}\) J kg–1 K–1
Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is held at a temperature of \(100^\circ \text{C}\) while the other one is kept at \(0^\circ \text{C}.\) If the two are brought into contact, assuming no heat loss to the environment, the final temperature that they will reach is:
1. | \(100^\circ \text{C}\) | 2. | less than \(50^\circ \text{C}\) |
3. | more than \(50^\circ \text{C}\) | 4. | \(0^\circ \text{C}\) |
A thin paper cup filled with water does not catch fire when placed over a flame. This is because:
1. | the water cuts off the oxygen supply to the paper cup |
2. | water is an excellent conductor of heat |
3. | the paper cup does not become appreciably hotter than the water it contains |
4. | the paper is a poor conductor of heat |
1. | \(\frac{4T}{5}\) | 2. | \(T\) |
3. | \(\frac{T}{2}\) | 4. | \(\frac{5T}{4}\) |
A sphere of \(0.047\) kg aluminium is placed for sufficient time in a vessel containing boiling water so that the sphere is at \(100^{\circ}\text{C}\). It is then immediately transferred to a \(0.14\) kg copper calorimeter containing \(0.25\) kg water at \(20^{\circ}\text{C}\). The temperature of water rises and attains a steady-state at \(23^{\circ}\text{C}\). The specific heat capacity of aluminium is:
(Given that: Specific heat capacity of copper calorimeter \(= 0.386\times 10^{3}~\text{J kg}^{-1}\text{K}^{-1}\) and the specific heat capacity of water \(s_w= 4.18\times 10^{3}~\text{J kg}^{-1}\text{K}^{-1})\)
1. \(1.811~\text{kJ kg}^{-1}\text{K}^{-1}\)
2. \(1.911~\text{kJ kg}^{-1}\text{K}^{-1}\)
3. \(0.811~\text{kJ kg}^{-1}\text{K}^{-1}\)
4. \(0.911~\text{kJ kg}^{-1}\text{K}^{-1}\)
In an experiment on the specific heat of a metal, a \(0.20~\text{kg}\) block of the metal at \(150^{\circ}\text{C}\) is dropped in a copper calorimeter (of water equivalent of \(0.025~\text{kg}\)) containing \(150~\text{cm}^{3}\) of water at \(27^{\circ}\text{C}.\) The final temperature is \(40^{\circ}\text{C}.\) The specific heat of the metal will be:
(Heat losses to the surroundings are negligible)
1. \(0 . 40 ~ \text{Jg}^{- 1} \text{K}^{- 1}\)
2. \(0 . 43 ~ \text{Jg}^{- 1} \text{K}^{- 1}\)
3. \(0 . 54 ~ \text{Jg}^{- 1} \text{K}^{- 1}\)
4. \(0 . 61 ~ \text{Jg}^{- 1} \text{K}^{- 1}\)
Assertion (A): | In a pressure cooker the water is brought to a boil. The cooker is then removed from the stove. Now on removing the lid of the pressure cooker, the water starts boiling again. |
Reason (R): | The impurities in water bring down its boiling point. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | Both (A) and (R) are False. |
In a steel factory, it is found that to maintain \(M\) kg of iron in the molten state at its melting point, an input power \(P\) watt is required. When the power source is turned off, the sample completely solidifies in time \(t\) seconds. The latent heat of the fusion of iron is:
1. \(\dfrac{2Pt}{M}\)
2. \(\dfrac{Pt}{2M}\)
3. \(\dfrac{Pt}{M}\)
4. \(\dfrac{PM}{t}\)