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VI SCIENCE AIR EVALUATION QUESTION ANSWERS
AIR
Evaluation
I. Choose the appropriate answer
1. __________ is the percentage of nitrogen in air.
a. 78%
b. 21%
c. 0.03%
d. 1%
Ans:a. 78%
2. Gas exchange takes place in plants using ___________.
a. Stomata
b. Chlorophyll
c. Leaves
d. Flowers
Ans: a. Stomata
3. The constituent of air that supports combustion is __________.
a. Nitrogen
b. carbon-di-oxide
c. Oxygen
d. water vapour
Ans: c. Oxygen
4. Nitrogen is used in the food packaging industry because it _________.
a. provides colour to the food
b. provides oxygen to the food
c. adds proteins and minerals to the food
d. keeps the food fresh
Ans: d. keeps the food fresh
5. _______ and ______ are the two gases, which when taken together, make up about 99 percentage of air.
I.Nitrogen II. carbon-di-oxide III. Noble gases IV. Oxygen
a. I and II
b. I and III
c. II and IV
d. I and IV
Ans: d. I and IV
II. Fill in the blanks
1. __________ is the active component of air.
Ans: Oxygen
2. The gas given out during photosynthesis is _________.
Ans: oxygen
3. __________ gas is given to the patients having breathing problems.
Ans: Oxygen
4. _______ can be seen moving in a beam of sunlight in a dark room.
Ans: Tiny dust particles
5. ________ gas turns lime water milky.
Ans: Carbon-di-oxide
III. True or False. If False, give the correct statement
1. Inhaled air contains a large amount of carbon-di-oxide.
Ans:False.
Inhaled air contains a large amount of oxygen.
2. Planting trees help in decreasing global warming.
Ans: True
3. The composition of air is always exactly the same.
Ans: False
The composition of air is not exactly the same always.
4. Whales come up to the water surface to breathe in oxygen.
Ans: True
5. The balance of oxygen in atmosphere is maintained through photosynthesis in animals and respiration in plants.
Ans: False
The balance of oxygen in atmosphere is maintained through photosynthesis in plants and respiration in animals.
IV. Match the following
Ans:
V. Arrange the following statements in correct sequence
1. Plants manufacture food by a process called photosynthesis.
2. Plants require energy for their growth.
3. Plants take in oxygen and release carbon-di-oxide just as animals.
4. Plants take carbon-di-oxide from the atmosphere, use chlorophyll in the presence of sunlight and prepare food.
5. Such oxygen is available to animals and human beings for breathing.
6. During this process, oxygen is released by plants.
Ans:
2.Plants require energy for their growth.
1.Plants manufacture food by a process called photosynthesis.
6.During this process, oxygen is released by plants.
3.Plants take in oxygen and release carbon-di-oxide just as animals.
5.Such oxygen is available to animals and human beings for breathing.
4.Plants take carbon-di-oxide from the atmosphere, use chlorophyll in the presence of sunlight and prepare food.
VI. Analogy
1. Photosynthesis : _____ :: Respiration :Oxygen
Ans: Carbon-di-oxide
2. 78% of air : Does not support combustion :: _____ : Supports
Combustion
Ans: 21% of air
VII. Observe the given figure carefully and answer the questions.
1. What will happen if we remove plants from the aquarium?
Ans:
Aquarium plants provide a natural food source, shelter, and most importantly help produce oxygen to fish and absorb the carbon dioxide and ammonia that is generated from the fish. Ultimately, aquarium plants help to maintain the natural eco cycle within the tank and allow fish to thrive and remain healthy.
2. What will happen if we remove the fish from the aquarium and keep it (with green plants) in a dark place?
Without the light, the plants cannot generate energy by photosynthesis for their growth and cannot produce oxygen to the aquarium.
VIII. Give very short answer
1. What is atmosphere? Name the five layers of atmosphere.
Our earth is surrounded by a huge envelope of air called the atmosphere.
The atmosphere is made up of five different layers
Troposphere,
stratosphere,
mesosphere,
ionosphere and
exosphere.
2. How do the roots of land plants get oxygen for breathing?
Air is present between the spaces of the soil. The roots of a plant take up oxygen from the air spaces between the soil particles.
3. What should be done if the clothes of a person catch fire accidentally? Why?
✱If clothes catches fire it will spread very quickly.
✱Fire rises up, so the person should cover his face with hands to protect the eyes and skin on the face.
✱Cover the person in a blanket/ sack and roll the person on the floor.
✱Roll backwards and forwards on the flame to smother the fire.
✱To reduce injury remove the burning fabric in a proper manner.
IX. Give short answer
1. Biscuits kept open on a plate during monsoon days lose its’ crispness. Why?
Biscuits will turn soft during the rainy season because biscuits contain less moisture content and tend to absorb moisture from the atmosphere.
So the biscuits lose their crispness.
2. Why do traffic assistants wear a mask on duty?
✱Traffic assistants are continually exposed to smoke emission of the vehicles.
✱Inhaling the particles suspended in the polluted air can cause breathing and lung problems.
✱So traffic assistants must wear masks to protect them from unnecessary health consequences.
X. Answer in detail
1. How do plants and animals maintain the balance of oxygen and carbon-dioxide in air?
Respiration in plants
Plants require energy for their growth and hence respiration also occurs in plants. During respiration, plants take in oxygen and release carbon–di–oxide, just as animals do.
Photosynthesis
Plants manufacture food by a process called photosynthesis. During photosynthesis, carbon-di-oxide from the air and water from the soil react in the presence of sunlight to produce food.
Plants release oxygen during photosynthesis which is much more than the oxygen consumed by the plants, during respiration.
Respiration in Animals
When we breathe in air, the oxygen present in the air reacts chemically with digested food within the body to produce carbon-di-oxide gas, water vapour and energy.
This cycle continues, so the oxygen and carbon-di-oxide in the air is always maintained, by the plant and animals.
2. Why is atmosphere essential for life on earth?
Atmosphere:
★Our earth is surrounded by a huge envelope of air called the atmosphere.
★Atmosphere extends to more than 800km above the surface of earth and is held in place by the earth’s gravity.
★The atmosphere protects us from many harmful rays coming from the sun.
★The air envelope is thicker near the earth’s surface and as we go higher the density and the availability of air gradually decreases.
★This is because, as we go higher, the force of gravity decreases, so it is not able to hold a large amount of air.
The atmosphere is made of five different layers – the troposphere, the stratosphere, the mesosphere, the ionosphere and the exosphere.
Troposphere:
★The troposphere is the layer closest to the earth.
★It is the layer in which we live. It extends upwards for about 16km above the surface of the earth.
★Movement of wind takes place in this layer.
★It also contains water vapour, which is responsible for making clouds. ★This layer is responsible for the weather we experience on earth.
★Aircrafts usually fly above this layer to avoid strong winds and bad weather.
Stratosphere:
★The stratosphere lies above the troposphere.
★This layer has the ozone layer in it.
★The ozone layer protects all life on earth from the harmful ultraviolet rays of the sun.
XI. Question based on Higher Order Thinking Skills
1. Can you guess why fire extinguishers throw a stream of carbon-di-oxide while putting - off fire?
Carbon Dioxide extinguishers are filled with non-flammable carbon dioxide gas under extreme pressure.
The pressure in the cylinder is so great bits of dry ice may shoot out the horn, while using.
CO2s are designed for Class B and C (flammable liquid and electrical) fires only.
Carbon dioxide extinguishes work by displacing oxygen and controls the fire.
The carbon dioxide is also very cold as it comes out of the extinguisher, so it cools the fuel as well.
