InterviewSolution
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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.
| 51. |
Choose the correct statement from the following :A. conversion of solid into vapours without passing through the liquid state is called vapourisation.B. conversion of vapours into solid without passing through the liquid state is called sublimation.C. conversion of vapours into solid without passing through the liquid state is called freezing.D. conversion of solid into liquid is called sublimation. |
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Answer» Correct Answer - D It is the correct statement. |
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| 52. |
The boiling points of diethyl ether, acetone and n-butyl alcohol are `35^(@)C, 56^(@)C " and" 118^(@)C` respectively. Which one of the following correctly represents their boiling points in kelvin scale ?A. 306 K, 329 K, 391 KB. 308 K, 329 K, 392 KC. 308 K, 329 K and 391 KD. 329 K, 392 K and 308 K. |
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Answer» Correct Answer - C It is the correct representation of the boiling points and is obtained by adding 273 K to the given temperature. |
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| 53. |
Give reasons for the following : (a) A liquid generally flows easily. (b) Ice at `0^(@)C` appears colder in the mouth than water at `0^(@)C`. (c ) Doctors advise to put strips of wet cloth on the forehead of a person having high fever. |
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Answer» (a) The intermolecular forces in a liquid are weak. Its molecules are able to slide over one another and liquid generally flows easily. (b) Latent heat of fusion of ice is quite high. In the mouth, ice absorbs this heat and melts. That is why ice at `0^(@)C` gives more cooling sensation in the mouth than water at the same temperature. (c ) As water evaporates from the strips of wet cloth placed on the forehead of a person, it absorbs heat from the body. The body temperature gets lowered and the person get some relief from fever. |
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| 54. |
Define (a) Latest heat of fusion. (b) Melting point (c ) Fusion. |
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Answer» (a) Latent heat of fusion : It is the amount of heat energy which is needed to convert one kg of a solid into the liquid state at its melting point temperature without any rise in temperature under one atmosphere pressure. (b) Melting point : It is the temperature at which a solid starts melting or starts changing into the liquid state. (c ) Fusion : The process of the change of the solid state into the liquid state is known as fusion. |
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| 55. |
When heat is constantly supplied by a gas burner with small flame to melt ice, then the temperature of ice during melting :A. increase very slowlyB. does not increase at allC. first remains constant and then increasesD. increases to form liquid water |
| Answer» Correct Answer - B | |
| 56. |
When water at `0^(@)C` freezes to form ice at the same temperature of `0^(@)C`, then it :A. absorbs some heatB. releases some heatC. neither absorbs nor releases heatD. absorbs exactly `3.34 xx 10^(5) J//kg` of heat |
| Answer» Correct Answer - B | |
| 57. |
If the temperature of an object is 268 K, it will be equivalent to :A. `- 5^(@)C`B. `+ 5^(@)C`C. `368^(@)C`D. `- 25^(@)C` |
| Answer» Correct Answer - A | |
| 58. |
The latent heat of vaporisation of water is :A. `2.25 xx 10^(6) J//kg`B. `3.34 xx 10^(6) J//kg`C. `22.5 xx 10^(4) J//kg`D. `33.4 xx 10^(5) J//kg` |
| Answer» Correct Answer - A | |
| 59. |
When heat is constantly supplied by a burner to boiling water, then the temperature of water during vaporisation :A. rises very slowlyB. rises rapidly until steam is producedC. first rises and then becomes constantD. does not rise at all |
| Answer» Correct Answer - D | |
| 60. |
Which of the following process/processes release heat ? (i) condensation (ii) vaporisation (iii) freezing (iv) meltingA. only (i)B. only (iv)C. (i) and (iii)D. (ii) and (iv) |
| Answer» Correct Answer - C | |
| 61. |
What is meant by saying that latent heat of vaporisation of water to `226kj//kg^(-1)`. |
| Answer» This means that when one kg of water at its boiling point temperature changes into steam, 226 kj of heat is absorbed. | |
| 62. |
In which state of matter (a) Intermolecular forces are the maximum. (b) Diffusion is the least (c ) Intermolecular spaces are the maximum ? |
| Answer» (a) Solid state (b) Solid state (c ) Gaseous state. | |
| 63. |
Which of the following shows the correct order of increasing intermolecular forces of attractions ?A. water ` lt ` Air ` lt ` Petrol `lt ` KeroseneB. Petrol `gt ` Water ` gt ` Kerosene ` gt` AirC. Water ` gt` Petrol ` gt` Air ` gt` KeroseneD. Air ` lt` Petrol `lt` Kerosene ` lt` Water |
| Answer» Correct Answer - D | |
| 64. |
The force that binds the particles of matter together is known asA. intermolecular spaceB. bondC. intermolecular forceD. nuclear force |
| Answer» Correct Answer - C | |
| 65. |
Explain the interconversion of three states of matter in terms of force of attraction and kinetic energy of the molecules. |
| Answer» The inertmolecular force of attraction is maximum in the solid state and minimum in the gaseous state. Similarly, the kinetic energy of the molecules is minimum in the solid state and maximum in the gaseous state. The change of state can be brought about by either changing the temperature or pressure. | |
| 66. |
Carbon dioxide was taken in an enclosed cylinder and compressed by applying pressure (a) Which state of matter will we obtain after completion of the process ? (b) Name and define this process. (c ) What is the common name of the product obtained in the above process ? |
| Answer» (a) Liquid state of matter will be obtained. (b) The process is known as liquefication. It is the change of state from gas to the liquid by increasing pressure or decreasing temperature. (c ) It is known as liquid `CO_(2)`. | |
| 67. |
Give reason for the following : (a) Gases fill up completely the vessel in which they are kept. (b) Gases exert pressure on the walls of the containing vessel. |
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Answer» (a) Particles constituting gases are very fast moving and diffuse at a fast speed. They therefore, readily fill up the vessel completely in which these are kept. (b)j Particles of gases collide against the walls of the containing vessel and impart momentum to them. This is responsible for the pressure of the gas. |
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| 68. |
`CO_(2)` is gas. Justify the given statement by two reasons. |
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Answer» (i) `CO_(2)` does not have a fixed volume. It can be compressed on applying pressure. (ii) `CO_(2)` does not have a fixed shape. It can take the shape of any container in which it is put. |
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| 69. |
Answer the following questions : (a) Why is ice at 273 K more effective in cooling than water at the same temperature ? (b) Name the two gases which are supplied in compressed form in homes and hospitals. (c ) What is dry ice ? |
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Answer» (b) LPG (Liquid Petroleum Gas) is supplied in homes while liquefied oxygen in hospitals (c ) Solid carbon dioxide `(CO_(2))` is known as dry ice. It is so named as it does not wet a piece of paper or cloth. |
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| 70. |
Which of the following statements do not express the properties of a solid? (i) The particles of a solid have high energy. (ii) The interparticle forces of attraction in a solid are very weak. (iii) A solid melts at a fixed temperature. (iv) The fluidity of a solid is very high.A. (i) and (ii) onlyB. (i), (ii) and (iv)C. (ii) and (iii) onlyD. (iii) and (iv) only |
| Answer» Correct Answer - B | |
| 71. |
Convert the following temperatures to the celsius scale. (a) 300k (b) 573k. |
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Answer» `300K=(300-273)^(@)`C `=27^(@)C` 573K=`(573-273)^(@)`C |
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| 72. |
What is the physical state of water at: a. `250^(@)C` b. `100^(@)C`? |
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Answer» Gaseous State (As Boiling temperature of the water is `100^(@)` C) Since water boils at this temperature thus it can exist in both liquid and gaseous form. At this temperature, after getting the heat equal to the latent heat of vaporisation,water starts changing from liquid state to gaseous state |
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| 73. |
Which of the following are matter? Chair, air,love, smell, hate, atmonds, thought, cold, lemon water, smell of perfume |
| Answer» Chair, air, almonds and cold drink | |
| 74. |
Why do people sprinkel water on a roof after a hot summer day ? |
| Answer» Water has a large heat of vporisation. In a hot summer day, the roof is quite hot. Water absorbs a large amount of heat from the roof for its vaporisation. The roof gets sufficiently cool and one can sleep comfortably. | |
| 75. |
What produces more severe burns - boiling water or steam ? |
| Answer» When water changes into steam at its boiling point, it absorbs latent heat of vaporisation (which is `22.5 xx 10^(5)` joules per kilogram). This means that steam at `100^(@)C` contains much more heat (in the form of latent heat) than boiling water at the same temperature of `100^(@)C`. So, when steam falls on our skin and condenses to form water, it gives out much more heat than boiling water, it causes more severe burns. | |
| 76. |
Why does our palm feel cold when we put some acetone or petror or perfume on it? |
| Answer» Both acetone and perfume are low boiling liquids. When any of them is poured on the palm, it readily changes into vapours or evaporates. For this, it needs some energy which is taken from the palm. The temperature of the palm gets lowered and we get a cooling sensation. | |
| 77. |
During summer days, water kept in an earthen pot (pitcher) becomes cool because of the phenomenon of :A. diffusionB. transpirationC. osmosisD. evaporation |
| Answer» Correct Answer - D | |
| 78. |
The matter in our surroundings exists in three states, ……. in liquids and …….. in gases. |
| Answer» solid, liquid, gaseous | |
| 79. |
The best evidence for the existence and movement of particles in liquids was provided by :A. John DaltonB. Ernest RutherfordC. JJ. ThomsonD. Robert Brown |
| Answer» Correct Answer - D | |