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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 351. |
Find the result of mixing 10 g of ice at - 10℃ with 10 g of water at 10℃. Specific heat capacity of ice = 2.1 J kg-1 K-1, Specific latent heat of ice = 336 J g-1 and specific heat capacity of water = 4.2 J kg-1 K-1 |
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Answer» Let whole of the ice melts and let the final temperature of the mixture be ToC. Amount of heat energy gained by 10g of ice at -10oC to raise its temperature to 0oC = 10 × 10 × 2.1 = 210J Amount of heat energy gained by 10g of ice at 0oC to convert into water at 0oC = 10 × 336 = 3360 J Amount of heat energy gained by 10g of water (obtained from ice) at 0oC to raise its temperature to ToC = 10 × 4.2 × (T − 0) = 42T. Amount of heat energy released by 10g of water at 10oC to lower its temperature to ToC = 10 x 4.2 x (10 − T) = 420 − 42T Heat energy gained = Heat energy lost 210 + 3360 + 42T = 420 − 42T T = −37.5oC This cannot be true because water cannot exist at this temperature. So whole of the ice does not melt. Let m gm of ice melts. The final temperature of the mixture becomes 0oC. So, amount of heat energy gained by 10g of ice at -10oC to raise its temperature to 0oC = 10 x 10 x 2.1 = 210J Amount of heat energy gained by m gm of ice at 0oC to convert into water at 0oC = m x 336 = 336m J Amount of heat energy released by 10g of water at 10oC to lower its temperature to 0oC = 10 x 4.2 x 10 − 0) = 420 Heat energy gained = Heat energy lost 210 + 336m = 420 m = 0.625 gm |
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| 352. |
The greater the mass of a body, the greater is its specific heat capacity. True of false? |
| Answer» False. The specific heat capacity is the characteristic property of the material of the body and not of the body. | |
| 353. |
Name the S.I. unit of heat. |
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Answer» S.I. unit of heat is joule (symbol J). |
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| 354. |
Define calorie. |
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Answer» CALORIE : “Is the amount of heat energy required to raise the temperature of 1g of water from 14.5°C to 15.5°C”. |
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| 355. |
Define the term calorie. How is it related to joule? |
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Answer» One calorie of heat is the heat energy required to raise the temperature of 1 g of water from 14.5oC to 15.5 oC. 1 calorie = 4.186 J |
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| 356. |
Define one kilo-calorie of heat. |
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Answer» One kilo-calorie of heat is the heat energy required to raise the temperature of 1 kg of water from 14.5oC to 15.5oC. |
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| 357. |
State the modern unit of heat energy. How is this unit related to calorie? |
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Answer» Modern unit of heat energy is joule Relation of joule with calorie : 1J = 2.4 calorie or 1 calorie = 4 .186J = 4.2J(approx) |
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| 358. |
What do you understand by the term thermal capacity? |
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Answer» Thermal capacity : “The amount of heat energy required to raise the temperature of a given mass of substance through 1°C (1k) is called thermal capacity”. |
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| 359. |
Why does snow/ice not melt rapidly on the mountains during summer? Explain. |
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Answer» Reasons used : 1kg of ice on meting absorbs 336000J of heat energy and 1kg of water to freeze will absorb 336000J of heat energy. It is the high latent heat of ice (336000J) for every 1kg to change into under at 0°C. Snow melts slowly on the mountains in summer and water is available in the rivers. |
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| 360. |
Why are icebergs carried thousands of kilometers away without melting substantially? Explain. |
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Answer» Reasons used : 1kg of ice on meting absorbs 336000J of heat energy and 1kg of water to freeze will absorb 336000J of heat energy. Specific latent heat of ice and also density of ice (less than water) makes it flow in water and ice bergs lose heat slowly and are carried to large distance. |
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