Q1: What are the three states of matter? (a) Solid, air, and water (b) Solid, liquid, and gas (c) Solid, vapour, and oxygen (d) Gas, nitrogen, and liquid
Solution:
Ans: (b) Explanation: Matter exists in three states: solids, liquids, and gases. These states depend on how tiny particles are arranged in matter.
Q2: Which gas is most abundant in air? (a) Oxygen (b) Carbon dioxide (c) Nitrogen (d) Argon
Solution:
Ans: (c) Explanation: Nitrogen is the most abundant gas in air, followed by oxygen. Air is a mixture of different gases in the atmosphere.
Q3: What happens to air when it is heated? (a) It contracts and takes less space (b) It expands and takes more space (c) It becomes solid (d) It becomes liquid
Solution:
Ans: (b) Explanation: Air expands when heated because its particles move faster and spread out, taking up more space than before.
Q4: Through which part do plants breathe? (a) Roots (b) Flowers (c) Stomata (d) Stems
Solution:
Ans: (c) Explanation: Plants breathe through stomata, which are tiny openings found on the lower surface of their leaves, helping them take in air.
Q5: Which gas do plants use for photosynthesis? (a) Nitrogen (b) Oxygen (c) Argon (d) Carbon dioxide
Solution:
Ans: (d) Explanation: Carbon dioxide is used by plants for photosynthesis. This gas is present in small amounts in the air we breathe.
Fill in the Blanks
Q1: Air is _____ and odourless.
Solution:
Ans: colourless
Q2: Water vapour is the gaseous form of _____.
Solution:
Ans: water
Q3: An inflated balloon is _____ than a deflated one because air has weight.
Solution:
Ans: heavier
Q4: Aquatic animals mostly breathe through _____.
Solution:
Ans: gills
Q5: Humans breathe through their _____.
Solution:
Ans: nose
True or False
Q1: Matter has mass and takes up space.
Solution:
Ans: True Explanation: Matter is defined as anything that has mass and takes up space, existing in three different states.
Q2: Oxygen is not necessary for burning processes.
Solution:
Ans: False Explanation: Oxygen is necessary for burning processes. Air supports burning because of the oxygen it contains in the atmosphere.
Q3: Insects breathe through spiracles.
Solution:
Ans: True Explanation: Insects, like ants, breathe through spiracles. These are tiny openings that help insects take in air for survival.
Q4: Air pollution is caused only by natural events.
Solution:
Ans: False Explanation: Air pollution can be caused by natural events or human activities. Human activities are the main cause of pollution.
Q5: Planting more trees helps keep air clean and fresh.
Solution:
Ans: True Explanation: Planting more trees is a preventive measure to keep air clean and fresh, reducing pollution in our environment.
Match the Following
Column A
Column B
1. Matter
A. Gaseous form of water present in air
2. Air pollution
B. Loss of water from plants as vapour
3. Water vapour
C. Anything that has mass and occupies space
4. Spiracles
D. Mixing of smoke and harmful gases with air
5. Transpiration
E. Breathing openings of insects
Solution:
Ans:
1 - C: Matter → Anything that has mass and occupies space
2 - D: Air pollution → Mixing of smoke and harmful gases with air
3 - A: Water vapour → Gaseous form of water present in air
4 - E: Spiracles → Breathing openings of insects
5 - B: Transpiration → Loss of water from plants as vapour
Short Answer Questions
Q1: What is matter and what are its three states?
Solution:
Ans: Matter is anything that has mass and takes up space. It exists in three states: solids, liquids, and gases. Substances are classified based on their properties, which depend on the arrangement of tiny particles. In solids, particles are tightly packed giving them a fixed shape.
Q2: What is the composition of air?
Solution:
Ans: Air is a mixture of gases in the Earth's atmosphere. The main gases are nitrogen and oxygen. Nitrogen is the most abundant gas, followed by oxygen. Air also contains small amounts of carbon dioxide, argon, and other gases. Water vapour, the gaseous form of water, is also present.
Q3: Why is oxygen important for living things?
Solution:
Ans: Oxygen is essential for humans and animals to breathe and survive. It is necessary for burning processes. Without oxygen, we cannot live. All living things require air to live. Oxygen from air helps our body work properly and gives us energy to do different activities.
Q4: How do different living things breathe?
Solution:
Ans: Different living things breathe in different ways. Plants breathe through stomata on the lower surface of their leaves. Aquatic animals mostly breathe through gills. Insects, like ants, breathe through spiracles. Humans breathe through their nose, with inhalation taking in air and exhalation releasing air out.
Q5: What are some ways to prevent air pollution?
Solution:
Ans: We can prevent air pollution by saving electricity, planting more trees, and using renewable energy like wind and solar. We should use public transport or walk for short distances. Using CNG and LPG as vehicle fuels reduces harmful emissions. We should dispose of garbage properly and maintain cleanliness around us.
Ans. Air is a mixture of gases that surrounds the Earth, primarily consisting of nitrogen, oxygen, carbon dioxide, and other trace gases. It is essential for life as it provides the oxygen needed for respiration.
2. Why is oxygen important for living organisms?
Ans. Oxygen is crucial for living organisms because it is used in the process of respiration, where it helps convert food into energy. This energy is vital for growth, reproduction, and maintenance of bodily functions.
3. How does air pressure change with altitude?
Ans. Air pressure decreases with an increase in altitude. As one goes higher in the atmosphere, the density of air molecules decreases, leading to lower pressure. This is why mountain climbers need supplemental oxygen at high altitudes.
4. What are the components of air?
Ans. The main components of air include approximately 78% nitrogen, 21% oxygen, and small amounts of argon, carbon dioxide, and other gases. Water vapour is also present in varying quantities.
5. How does pollution affect air quality?
Ans. Pollution negatively impacts air quality by introducing harmful substances such as particulate matter, carbon monoxide, sulphur dioxide, and nitrogen oxides into the atmosphere. This can lead to health problems and environmental issues, such as acid rain and global warming.
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