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Quiz Chapter 7: Air

10 questions ยท Form 1 Science Bab 7: Air

Question 1 of 10Score: 0

How does spraying cold water onto a wood fire put it out?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. How does spraying cold water onto a wood fire put it out?

  1. It converts wood fuel into carbon dioxide
  2. It cools the fuel below its ignition temperature
  3. It generates oxygen gas to overwhelm the fire
  4. It reacts chemically to dissolve the charcoal
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Answer: B

Water absorbs significant heat energy as it turns to steam, lowering the temperature of the burning wood below its ignition threshold.

2. Why is carbon monoxide gas extremely dangerous to human health?

  1. It causes skin burns on contact
  2. It combines with hemoglobin in blood, reducing oxygen transport
  3. It destroys human lung tissue instantly
  4. It triggers severe allergic reactions on eyes
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Answer: B

Carbon monoxide binds strongly with hemoglobin to form carboxyhemoglobin, preventing red blood cells from carrying oxygen.

3. What effect does haze have on the surrounding environment?

  1. Increases atmospheric oxygen level
  2. Reduces visibility and causes respiratory difficulties
  3. Prevents soil erosion
  4. Neutralizes acid rain
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Answer: B

Haze consists of suspended fine particulate matter like soot and dust, severely reducing visibility and triggering asthma/respiratory issues.

4. Which pollutant gas is primarily responsible for the depletion of the earth's ozone layer?

  1. Chlorofluorocarbons (CFCs)
  2. Carbon dioxide
  3. Sulfur dioxide
  4. Methane
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Answer: A

Chlorofluorocarbons (CFCs) release chlorine radicals that react with and break down protective ozone ($O_3$) molecules.

5. Which gas present in air is essential for green plants to undergo photosynthesis?

  1. Oxygen
  2. Nitrogen
  3. Carbon dioxide
  4. Argon
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Answer: C

Green plants absorb carbon dioxide from the air to synthesize glucose during photosynthesis.

6. How does a carbon dioxide fire extinguisher extinguish a flame?

  1. By lowering the temperature of the fuel below its ignition point
  2. By displacing oxygen and cutting off the oxygen supply
  3. By chemically absorbing the fuel source
  4. By increasing atmospheric pressure around the fire
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Answer: B

Carbon dioxide gas is denser than air and non-combustible; it smothers the fire by preventing oxygen from reaching the fuel.

7. Which air pollutant is produced by incomplete combustion of carbon fuels in vehicle exhausts?

  1. Carbon dioxide
  2. Sulfur dioxide
  3. Carbon monoxide
  4. Methane
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Answer: C

Incomplete combustion releases carbon monoxide (CO), a colorless, odorless, toxic gas.

8. Which gas glows with a bright orange-red light when electric current passes through it in neon signage?

  1. Helium
  2. Neon
  3. Argon
  4. Nitrogen
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Answer: B

Neon gas emits a distinct reddish-orange glow when electrified in discharge tubes used for advertising signs.

9. Which two gases dissolve in rainwater to form acid rain?

  1. Oxygen and Carbon monoxide
  2. Sulfur dioxide and Nitrogen dioxide
  3. Carbon dioxide and Helium
  4. Methane and Ozone
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Answer: B

Sulfur dioxide and nitrogen dioxide dissolve in atmospheric moisture to form sulfuric acid and nitric acid, producing acid rain.

10. Which gas is released back into the atmosphere solely through the process of photosynthesis?

  1. Carbon dioxide
  2. Oxygen
  3. Nitrogen
  4. Water vapor
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Answer: B

Photosynthesis by green plants is the primary biological process that produces and releases oxygen into the air.

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