1. Which of the subsequent assertions is untrue?
(A) Air is necessary for breathing in all living things.
(b) Air is something we can sense but not see.
(c) Kites can be flown because air is moving.
(d) Although soil doesn't contain air, everything else does.
1. Which of the subsequent assertions is untrue?
(A) Air is necessary for breathing in all living things.
(b) Air is something we can sense but not see.
(c) Kites can be flown because air is moving.
(d) Although soil doesn't contain air, everything else does.
Explanation:
(d) Despite not being in soil, air is present everywhere.
In nature, air is everywhere, even earth, and it permeates all space. One straightforward exercise can demonstrate this.
We can observe the water's absorption in the form of bubbles in the soil by placing a lump of dry soil in a beaker or glass and adding water to it.
2. Which of the following cannot be moved by the wind?
(a) Firki
(b) Weathercock
(c) Ceiling fan
(d) Yacht for sailing
2. Which of the following cannot be moved by the wind?
(a) Firki
(b) Weathercock
(c) Ceiling fan
(d) Yacht for sailing
Explanation:
(d) Ceiling fan
As ceiling fans are powered by electricity, wind is not helpful in moving them.
3. What about the air is untrue?
(a) It causes the windmill to rotate.
(b) It facilitates aeroplane movement.
(c) Because air is present, birds can fly.
(d) The water cycle is unaffected by it.
3. What about the air is untrue?
(a) It causes the windmill to rotate.
(b) It facilitates aeroplane movement.
(c) Because air is present, birds can fly.
(d) The water cycle is unaffected by it.
Explanation:
(d) It doesn't play a part in the water cycle.
The water cycle is significantly influenced by air. To create clouds, water vapour rises to the surface.
4. Mountaineers carry oxygen cylinders because: (a) there is no oxygen on high mountains; (b) there is a lack of oxygen on mountains at high altitudes; (c) oxygen is used for cooking; and (d) oxygen keeps them warm at cold temperatures.
4. Mountaineers carry oxygen cylinders because: (a) there is no oxygen on high mountains; (b) there is a lack of oxygen on mountains at high altitudes; (c) oxygen is used for cooking; and (d) oxygen keeps them warm at cold temperatures.
Explanation:
(b): High-altitude mountains suffer from an oxygen shortage.
The atmosphere becomes thinner and there is less oxygen available as we ascend. This makes breathing harder in mountainous and hilly areas. Consequently, mountaineers bring oxygen cylinders with them while they ascend steep mountains.
5. Boojho put an empty plastic bottle into a pail of water while it was upside down and with its mouth open. He then slightly tipped the bottle and noted what follows.
(i) The bottle released air bubbles.
(ii) The bottle contained some water.
(iii) Bubbles of nitrogen gas emerged, and oxygen was dissolved in the water.
(iv) Just water entered the bottle; no bubbles appeared.
Which conclusion(s) is/are true?
(a) (i) and (ii) (b) (iv) alone (c) (iii) and (iv) (d) (i) alone.
5. Boojho put an empty plastic bottle into a pail of water while it was upside down and with its mouth open. He then slightly tipped the bottle and noted what follows.
(i) The bottle released air bubbles.
(ii) The bottle contained some water.
(iii) Bubbles of nitrogen gas emerged, and oxygen was dissolved in the water.
(iv) Just water entered the bottle; no bubbles appeared.
Which conclusion(s) is/are true?
(a) (i) and (ii) (b) (iv) alone (c) (iii) and (iv) (d) (i) alone.
Explanation:
(a): I and (ii)
Air bubbles erupted from the bottle. The bottle was flooded with water.
6. The atmosphere has the highest concentration of which of the following air constituents?
(a) Nitrogen (b) Oxygen (c) Carbon dioxide (d) Water vapour
6. The atmosphere has the highest concentration of which of the following air constituents?
(a) Nitrogen (b) Oxygen (c) Carbon dioxide (d) Water vapour
Explanation:
(a) Nitrogen
Most of the nitrogen in the atmosphere is found in the atmosphere. 78% of it is nitrogen, 21% is oxygen, and the remaining 1% is made up of dust particles, carbon dioxide, water vapour, and a few other gases.
7. The airborne substances that are detrimental to living things.
(a) Nitrogen and carbon dioxide
(b) dust and water vapour
(c) smoke and water vapour
(d) dust and smoke
7. The airborne substances that are detrimental to living things.
(a) Nitrogen and carbon dioxide
(b) dust and water vapour
(c) smoke and water vapour
(d) dust and smoke
Explanation:
(c): Smoke and dust
The water cycle in nature depends on water vapour.
Plants require nitrogen to survive.
Photosynthesis depends on carbon dioxide.
As a result, the smoke and dust emissions from manufacturers pose a serious threat to human health.
8. Usha placed a piece of dry dirt in a glass and filled it with water until it was fully submerged. She noticed bubbles erupting.
(a) water vapour
(b) only oxygen gas
(c) air
(d) none of these
8. Usha placed a piece of dry dirt in a glass and filled it with water until it was fully submerged. She noticed bubbles erupting.
(a) water vapour
(b) only oxygen gas
(c) air
(d) none of these
Explanation:
(c): air
The soil absorbs the water in the form of bubbles when it is put on the lump of soil.
9. Indicate the truth or falsity of the following assertions. Correct them if they're untrue.
(A) Plants need oxygen to breathe.
(a) While producing their own food, plants create oxygen.
(c) Air aids in the motion of gliders and sailing yachts but has no bearing on the flight of birds or aeroplanes.
(d) Space is not taken up by air.
9. Indicate the truth or falsity of the following assertions. Correct them if they're untrue.
(A) Plants need oxygen to breathe.
(a) While producing their own food, plants create oxygen.
(c) Air aids in the motion of gliders and sailing yachts but has no bearing on the flight of birds or aeroplanes.
(d) Space is not taken up by air.
Explanation:
(a) True
(b) True
(c) False - Air aids in bird and aeroplane flight, as well as the movement of sailing boats and gliding craft.
(d) Air does occupy space, hence false.
10. Air is a key component in many musical instruments. Describe a few of these instruments.
10. Air is a key component in many musical instruments. Describe a few of these instruments.
Explanation:
Several musical instruments, including the mouth organ, harmonium, shehnai, trumpet, and flute, rely heavily on air.
11. The letters of certain words become mixed up in the boxes of a column I. Put them in the boxes provided in column II in the correct order.
11. The letters of certain words become mixed up in the boxes of a column I. Put them in the boxes provided in column II in the correct order.
Explanation:
12. Use the words provided to construct sentences.
(a) 99%, oxygen, nitrogen, together
(b) dissolved, animals, air, aquatic
(c) Air, wind, motion, termed
12. Use the words provided to construct sentences.
(a) 99%, oxygen, nitrogen, together
(b) dissolved, animals, air, aquatic
(c) Air, wind, motion, termed
Explanation:
(a) Oxygen and nitrogen combined make up 99% of the air.
(b) Aquatic animals breathe using dissolved air.
(c) The wind is the term for the moving air.
13. There is a box with a list of terms. Fill in the gaps in the sentences below with the proper words.
[Air, oxygen, water vapour, wind, combination, direction, route, bottles, and cylinders]
(a) The windmill rotates because of.
(b) One of some gases is air.
(c) A weathercock depicts the direction the air is moving in that location.
(c) Mountaineers who ascend high mountains do so while carrying oxygen.
13. There is a box with a list of terms. Fill in the gaps in the sentences below with the proper words.
[Air, oxygen, water vapour, wind, combination, direction, route, bottles, and cylinders]
(a) The windmill rotates because of.
(b) One of some gases is air.
(c) A weathercock depicts the direction the air is moving in that location.
(c) Mountaineers who ascend high mountains do so while carrying oxygen.
Explanation:
(a) wind
(b) mixture
(c) direction
(d) cylinders
14. Carefully examine the image in Fig. 15.1 and respond to the following questions.
(A) What is covering the police officer's mouth and nose?
(b) Why does he have his nose covered?
(c) What can you say about the air quality in the area depicted in Fig.15.1?
14. Carefully examine the image in Fig. 15.1 and respond to the following questions.
(A) What is covering the police officer's mouth and nose?
(b) Why does he have his nose covered?
(c) What can you say about the air quality in the area depicted in Fig.15.1?
Explanation:
(a) The police officer covers his mouth and nose with a mask.
(b) He has covered his nose with a mask to shield himself from dust and contaminated air. The mask keeps us from being exposed to car exhaust's toxic gases and dust particles, which keeps them from entering our bodies.
(c) Because the air is dirty, it has poor quality in the stated figure. The air is polluted because of the smoke, dangerous chemicals like carbon monoxide and sulphur dioxide, and dust particles released by automobiles.
15. Garima noticed that tiny bubbles appeared all over the inside of the tightly-capped water bottle when it was placed in the sunlight. Aid Garima in discovering what transpired.
15. Garima noticed that tiny bubbles appeared all over the inside of the tightly-capped water bottle when it was placed in the sunlight. Aid Garima in discovering what transpired.
Explanation:
Due to heat from the sun, air dissolves in water and escapes in the form of small bubbles. As a result, there were little bubbles forming all over the bottle.
16. Match the items of Column I with the items of column II.
Column I Column II
(a) Weathercock (i) Gases and fine dust particles
(b) Mountaineers (ii) Sailing yacht
(c) Fine hair inside the nose (iii) Oxygen cylinders
(d) Smoke (iv) The direction of airflow
(e) Wind (v) Prevent dust particles
16. Match the items of Column I with the items of column II.
Column I Column II
(a) Weathercock (i) Gases and fine dust particles
(b) Mountaineers (ii) Sailing yacht
(c) Fine hair inside the nose (iii) Oxygen cylinders
(d) Smoke (iv) The direction of airflow
(e) Wind (v) Prevent dust particles
Explanation:
: Column I Column II
(a) Weathercock (iv) The direction of airflow
(b) Mountaineers (iii) Oxygen cylinders
(c) Fine hair inside the nose (v) Prevent dust particles
(d) Smoke (i) Gases and fine dust particles
(e) Wind (ii) Sailing yacht
17. Briefly explain the ensuing observations.
(A) In a closed space, a firki cannot rotate.
(b) At a specific time, the weathercock's arrow is pointing in a specific direction.
(c) A glass that isn't full is actually not empty.
(d) Mouth breathing could be harmful to you.
17. Briefly explain the ensuing observations.
(A) In a closed space, a firki cannot rotate.
(b) At a specific time, the weathercock's arrow is pointing in a specific direction.
(c) A glass that isn't full is actually not empty.
(d) Mouth breathing could be harmful to you.
Explanation:
(a) The absence of air movement in a restricted space prevents a firki from rotating. Because to the moving air all around, a firki typically rotates when put in an open space.
(b) A weathercock is a device that displays the wind's direction. It is made up of an arrow that is positioned at its centre of gravity and can freely rotate around a vertical axis. In order to depict the most recent direction of the wind movement, the arrow points in a specific direction at a specific time.
(c) A glass that is empty is actually filled with air. A straightforward experiment in which an empty bottle is placed upside down in a beaker of water can be used to demonstrate it. When the bottle is pushed upside down, there is no room for air to leave, thus water does not enter the bottle. When the bottle is tilted, bubbles of air are able to escape, and water fills the empty area. This demonstrates that air fills even an empty glass.
(d) Yeah, mouth breathing might be harmful to us. The air may contain gases, water vapour, and dust particles. The fine hair and mucus in the nose keep dust particles from entering the respiratory tract when we breathe through our nostrils. But, if we breathe via our mouths, the dangerous dust particles may go inside of us and cause us to become ill. Thus, mouth breathing could be harmful to us.
18. If any of the following gases vanish from the atmosphere, create a hypothetical circumstance and write a few sentences about it.
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
18. If any of the following gases vanish from the atmosphere, create a hypothetical circumstance and write a few sentences about it.
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
Explanation:
(a) The absence of oxygen from the atmosphere would make life on earth impossible because it is crucial for the survival of all living things. While breathing, both plants and animals take in oxygen from the air and exhale carbon dioxide. Without oxygen, it becomes hard for living things to breathe, and as a result, they would eventually perish. Thus, oxygen is crucial.
(b) The atmosphere is primarily composed of nitrogen, which is incapable of supporting combustion. Everything on Earth will burn extremely quickly if nitrogen gas is removed from the atmosphere, which could have severe consequences. Although it cannot directly absorb nitrogen from the air, plants need it for growth. They either eat it directly or use fertilisers that may be absorbed by the soil to get it in soluble form. In order for plants, animals, people, and other species to flourish properly, nitrogen is crucial.
(c) Photosynthesis, the process by which plants produce their own food, requires carbon dioxide. The plants' inability to create food and their inability to release oxygen will disrupt the carbon dioxide-to-oxygen ratio in the atmosphere if carbon dioxide disappears from the atmosphere. Thus, without air and food, there won't be any life on earth.
19. Paheli heated some water that was held in a beaker. She saw that before the water began to boil, small bubbles emerged. She filled a bottle to the brim after boiling the water for about five minutes, then sealed the bottle securely until the water cooled to room temperature.
(a) What caused the little bubbles to form?
(b) Do you anticipate that when the water is removed from the bottle and heated, little bubbles will form? Explain your response.
19. Paheli heated some water that was held in a beaker. She saw that before the water began to boil, small bubbles emerged. She filled a bottle to the brim after boiling the water for about five minutes, then sealed the bottle securely until the water cooled to room temperature.
(a) What caused the little bubbles to form?
(b) Do you anticipate that when the water is removed from the bottle and heated, little bubbles will form? Explain your response.
Explanation:
As air dissolves in water,
(a) the minute bubbles developed before the water began to boil. As soon as the water began to boil, bubbles formed from the water's dissolved air.
(b) Because Paheli had completely boiled the water, allowing the water's air to leave, there will be no little bubbles when the water is reheated because there is no air in it.
20. A friend of Paheli's paid her a visit on a Sunday morning. She went to the nearby garden in search of some flowering plants. They both walked over to the garden. They noticed some blossoming plants by the highway on their way back from the garden. But to their astonishment, they discovered that these plants' leaves and blooms were comparatively very uninteresting. Can you assist them in learning why?
20. A friend of Paheli's paid her a visit on a Sunday morning. She went to the nearby garden in search of some flowering plants. They both walked over to the garden. They noticed some blossoming plants by the highway on their way back from the garden. But to their astonishment, they discovered that these plants' leaves and blooms were comparatively very uninteresting. Can you assist them in learning why?
Explanation:
The air quality in the open area, which includes dust particles released from automobiles, chimneys, and factories, may be the cause of the roadside plants' dull-appearing leaves and blossoms. The plant portions looked drab because the dust particles stuck to them.
