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.
| 1. |
Which among the following is not a homogeneous mixture ?A. solderB. aqueous solution of `NaCl`C. sulphur in carbon disuphideD. suphur in water |
| Answer» Sulphur is insoluble in water and forms a solid-liquids heterogenous mixture. | |
| 2. |
Which among the following is the false statement ?A. Water boils below `100^(@)` C on mountain peaks.B. Ice undergoes sublimation on surface of moon.C. Ice melts above `0^(@)`C on mountain peaks.D. Cooking of food is faster on mountain peaks |
| Answer» With increasing altitude , pressure ,and hence, cooking point of water alos decrease. As a result, cooking of food is delayed of food is delayed on mountain peaks. | |
| 3. |
In a chemistry lab, Rina took some mercury and water in two test tubes separately. Then she drained off both the liquids and on observing the emty test tubes, found some difference. Can you guess what the difference is ? Explain with appropriate reasons. |
| Answer» Water droplets are found on the inner surface of one test tube while the other test tube is completely dry. In the case of water, adhesive forces are more than cohesive forces but in case of mercury cohesive forces are more than ahesive forces. Due to stronger adhesive force, water droplets stick to the test tube. | |
| 4. |
Why does temperature remain constant as heated liquid gets converted to its gaseous state at its boiling point ? |
| Answer» When the heated liquid is converted to its gaseous state at its boiling point, the temperature remains constant because the change in state of matter is associated with increase in potential energy, and the kinetic energy remains constant. | |
| 5. |
The high diffusibility of gases is due toA. high intermolecular forces of attractionB. high KE of moleculesC. restricted translatory motion in upward directionD. all the above |
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Answer» Correct Answer - B b |
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| 6. |
Arrange the following changes of energy during following phase transition in a proper order. Ice `(0^(@) C) to "water "(50^(@)C) to "ice "(0^(@)C)` (1) potential energy increases and kinetic energy remains constant (2) potential energy decreases and kinetic energy remains constant (3) potential energy increases and kinetic energy increases (4) potential energy decreases and kinetic energy decreasesA. 4 2 3 1B. 1 3 2 4C. 1 3 4 2D. 3 4 1 2 |
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Answer» (i) potential enregy increase and kinetic energy remains constant. (ii) potential enregy increase and kientic energy increase. (iii) potential decrease and kinetic energy decreases. (iv) potential energy decreases and kinetic energy remains constant. |
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| 7. |
If we keep a box of ice creasm in a freezer for too long, crystals of ice are formed inside the box. Give reasons. |
| Answer» Due to very low temperature in the freezer, the water vapour gets deposited as crystals of ice. Therfore, we get crytals of ice inside the box if kept in freezer for longer time. | |
| 8. |
Gunpowder is a ________.A. solid-liquid homogeneous mixtureB. solid-liquid heterogeneous mixtureC. solid-solid homogeneous mixtureD. solid-solid heterogeneous mixture |
| Answer» Gunpowder is a heterogeneous mitxture of `KNO_(3)`, C and S. | |
| 9. |
What is the shape of the meniscus observed when water and mercury are taken in two different capillary tubes and why ? |
| Answer» Mercury shows a convex meniscus as it has higher cohesive forces than adhesive forces with glass. Water, on the other hand, shows a concave meniscus as the adhesive forces between water and glass are higher than the cohesive forces between water molecules. | |
| 10. |
When soda water bottle is kept open for sometime, it loses the tangy taste. Give reason. |
| Answer» At high pressure, more amount of `CO_2` is dissolved in water. When the bottle is opened, excess amount of `CO_2` comes out as solubility of gas decreases in pressure, and hence, the soda water loses its tangy taste. | |
| 11. |
In Darjeeling, distilled water boils at a temperatureA. above 373 KB. above 473 KC. below 373 KD. at 373 K |
| Answer» Pressure decreases with increase in altiude, and hence, boiling piont decrease. Since Darjeeling is at higher attidues, water boils 373k K, i.e., below `100^(@)C`. | |
| 12. |
Why is solid `CaCl_2` spread on roads in cold countries during winter season ? |
| Answer» effect of addition of `CaCl_2` on freezing point of `H_2O` | |
| 13. |
Among the following, identify the substance in which molecules posses viratory, rotatory and translatory motions in all directions except in one direction.A. bromineB. iodineC. ammoniaD. silicon dioxide |
| Answer» Bromine is a liquid. The molecules of liquid possess vibratroy, rotatory motion in all directions excepts except in upwards direciton . | |
| 14. |
The critical temperatures of `CO_2` gas and `N_2` gas are `31^(@)`C and `-147^(@)` C, respectively. Which gas is liquefied easily and why ? |
| Answer» Since the criticl temperature of `CO_2` is high, the intermolecular forces of attraction among `CO_2` molecules are more when compared to `N_2`. Hence, `CO_2` will liquefy easily. | |
| 15. |
When a mixture of three miscible liquids is subjected to fractional distillation, liquid B is obtained in the receiver flask. The remaining mixture on further fractional distillation, A, is left behind in the distillation flask. On the basis of the results, comment on the critical temperatures of A, B and C when they are in gaseous state. |
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Answer» (i) relation between intermolecular forces of attraction and boiling point (ii) relation between critical temperature and boiling point (iii) relation between intermolecular forces of attraction and boiling point (iv) relation between critical temperature and boiling point |
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| 16. |
Which of the following phenomena is based on the principle that cooling results due to evaporation ?A. formation of water drops on the surface of cold drink bottle.B. formation of crystals of ice on the inner surface of the lid of an ice cream box in freezerC. white foggy appearance on the surface of large ice blocksD. stretching out of tongues by dogs during summer |
| Answer» Doges stretch out their tongues during summer because the surface area fo the body from over-heating during summer. This is because they cannot sweat like humna being . All other phenomerna aer due to the condenstation of water vapour due to very low temperature. | |
| 17. |
Identify the mixture which can be separated by magnetic separated by magnetic separation method.A. chalk powder + sandB. iron + sandC. common salt + sandD. sulphur + sand |
| Answer» Since iron is magnetic in nature iron and sand mixture can be separted by magnetic separation. | |
| 18. |
Why molten silver cannot be used to make sharp castings ? |
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Answer» (i) durable characteristics of the metal for proper casting. (ii) Change observed in silver during phase transition . |
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| 19. |
Sodium cannot be preserved in water. However, sodium amalgan can be kept in water. Justify. |
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Answer» (i) predicting the order of vapour pressure of given compounds (ii) changes occuring when metal is preserved in water (iii) properties of sodium in amalgam (iv) effect of water on sodium amalgam |
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| 20. |
`H_2SO_4` is always diluted by adding it to water but not by adding water to it. Justify. |
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Answer» (i) energy changes involved in the reaction between `H_2SO_4 and H_2O` (ii) conditions required for controlling the reaction |
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