Heat and Energy Quiz - ICSE Class 9 Physics
Free practice quiz: Heat and Energy (ICSE Class 9 Physics). 47 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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A block of ice at -10°C is heated. Which of the following processes will occur at a constant temperature?
- Increase in temperature of ice
- Melting of ice
- Increase in temperature of water
- Boiling of water
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Answer: B. Melting of ice
When ice at -10°C is heated, its temperature will first increase until it reaches its melting point (0°C). At 0°C, the ice will start to melt into water. The melting process occurs at a constant temperature until all the ice has melted. After all ice has melted, the temperature of the water will then increase.
Which of the following phenomena demonstrates heat transfer by radiation?
- Feeling the warmth of a hot stove when you touch it.
- The circulation of water in a pot being heated from below.
- Feeling the warmth of the sun on your skin.
- The transfer of heat through a metal rod.
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Answer: C. Feeling the warmth of the sun on your skin.
Heat transfer by radiation does not require a medium. The sun's heat reaches the Earth through the vacuum of space via electromagnetic waves, which is radiation. Touching a hot stove is conduction. Water circulation in a pot is convection. Heat transfer through a metal rod is conduction.
A bimetallic strip is made of two metals with different coefficients of thermal expansion. When heated, the strip bends. This is because:
- Both metals expand by the same amount.
- One metal expands more than the other.
- Both metals contract.
- The strip becomes magnetic.
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Answer: B. One metal expands more than the other.
When a bimetallic strip is heated, the metal with the higher coefficient of thermal expansion will expand more than the metal with the lower coefficient. This differential expansion causes the strip to bend, with the more expansive metal on the outside of the curve.
When a substance undergoes a phase change from gas to liquid, it is called condensation. During condensation, the substance:
- Absorbs heat energy.
- Releases heat energy.
- Does not change temperature.
- Both absorbs heat and does not change temperature.
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Answer: B. Releases heat energy.
Condensation is an exothermic process, meaning it releases energy. This released energy is the latent heat of vaporization. For example, when steam condenses into water, it releases latent heat.
When ice melts into water, its density:
- Increases.
- Decreases.
- Remains the same.
- First increases then decreases.
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Answer: A. Increases.
The density of ice is approximately 920 kg/m³, while the density of liquid water at 0°C is approximately 1000 kg/m³. Therefore, when ice melts into water, its density increases.