Matter in Our Surroundings Class 9 MCQ With Answers Set-6
Q51. Which of the following is NOT an example of cooling by evaporation?
A. Pouring acetone on your palm
B. Sprinkling water on a hot roof
C. Using a fan to cool yourself
D. Eating ice cream
Answer – D. Eating ice cream
Explanation-Eating ice cream does not cool you down by evaporation. Instead, it cools you down by absorbing heat from your body.
Q52. Why do people wear cotton clothes in summer?
A. Because cotton is a good absorber of sweat.
B. Because cotton allows air to circulate.
C. Both A. and B.
D. None of the above
Answer – C. Both A. and (B)
Explanation-Cotton is a good absorber of sweat and allows air to circulate, which helps to keep you cool and dry in summer.
Q53. Why do we see water droplets on the outer surface of a glass containing ice-cold water?
A. Because the cold water cools the water vapor in the air, causing it to condense.
B. Because the water vapor in the air is attracted to the cold water.
C. Both A. and B.
D. None of the above
Answer – A. Because the cold water cools the water vapor in the air, causing it to condense.
Explanation-Condensation is the process of water vapor changing into a liquid state. When the cold water in the glass cools the water vapor in the air, it causes the water vapor to condense and form water droplets.
Q54. Which of the following is NOT a factor that affects the rate of cooling by evaporation?
A. Surface area
B. Temperature
C. Humidity
D. Wind speed
Answer – C. Humidity
Explanation-Humidity does not affect the rate of cooling by evaporation. It does, however, affect the rate of evaporation.
Q55. In all three states of water (i.e., ice, liquid, and vapor), what happens to the chemical composition of water?
A. It significantly differs.
B. It remains constant.
C. It varies occasionally.
D. None of the above.
Answer – B. It remains constant.
Explanation-In all three states of water (i.e., ice, liquid, and vapor), the chemical composition (H2O) of water remains consistent; only the physical state differs.
Q56. Which of the following statements is not accurate regarding the state of matter?
A. Gas particles have weak attraction forces.
B. Plasma consists of highly energetic and excited particles.
C. Plasma exhibits unique colors based on the gas nature.
D. Bose-Einstein condensate forms when a low-density gas is cooled.
Answer –D. Bose-Einstein condensate forms when a low-density gas is cooled.
Explanation-Bose-Einstein condensate is created by cooling a gas with extremely low density.
Q57. Which of the following is not a characteristic of gases?
A. Gases possess a definite shape.
B. Gases lack a definite volume.
C. Gases exhibit rapid diffusion.
D. Gas particles undergo random motion
Answer – A. Gases possess a definite shape.
Explanation-Gases, unlike solids and liquids, do not have a fixed shape or volume.
Q58. A form of matter that lacks a fixed shape but maintains a fixed volume. An example of this matter state is _________
A. Carbon dioxide
B. Ice
C. Water vapor
D. Kerosene
Answer – A form of matter that has no specific shape but retains a fixed volume is exemplified by a liquid state.
Explanation-D. kerosene
Q59. When heat is continuously supplied to boiling water by a burner, what happens to the water temperature during vaporization?
A. It gradually increases.
B. It rises rapidly until steam forms.
C. It initially rises and then stabilizes.
D. It remains unchanged.
Answer – D. It remains unchanged.
Explanation-The temperature remains constant during the vaporization process.
Q60. What is the boiling point of water at sea level?
A. 0℃
B. 273 K
C. 373 K
D. 273℃
Answer – C. 373 K
Explanation-The boiling point of water at sea level is 100℃ or 373K.
Q61. The process in which a solid changes directly into a vapor state is called ______
A. Vaporization
B. Solidification
C. Condensation
Answer – D. Sublimation
Explanation-Sublimation is the process in which a solid transforms directly into a vapor state.
Q62. Which solid undergoes sublimation?
A. Ice cube
B. Naphthalene
C. Sodium chloride
D. Potassium chloride
Answer – B. Naphthalene
Explanation-Naphthalene transforms directly from a solid state to a gaseous state without forming a liquid.
Q63. Which of the following phenomena increases with rising temperature?
A. Diffusion, evaporation, compression of gases
B. Evaporation, compression of gases, solubility
C. Evaporation, diffusion, expansion of gases
D. Evaporation, solubility, diffusion, compression of gases
Answer – C. Evaporation, diffusion, expansion of gases
Explanation-With increasing temperature, the phenomena of evaporation, diffusion, and gas expansion intensify.
Q64. What conditions are most favorable for converting gas into a liquid?
A. High pressure, low temperature
B. Low pressure, low temperature
C. Low pressure, high temperature
D. High pressure, high temperature
Answer – A. High pressure, low temperature
Explanation-Gas is converted into a liquid under high-pressure and low-temperature conditions.
