Chhattisgarh State Board Class 8 Science Chapter 3 Air Exercise Fill in the Blanks, True or False , Questions and Answers here.
(1) Air is a mixture of gases what are they?
Ans:- Air is a mixture of gases. They are nitrogen, oxygen, argon, water vapour, carbon dioxide, sulphur dioxide and other gases.
(2) What is ozone layer? What is its importance?
Ans:- Ozone layer is found above the earth surface. It’s distance about 16 to 23 kilometre.
It’s very important in our life. This layer blocks the harmful ultra violet rays. Thus the ozone layer helps in protecting us from skin cancer.
(3) Which are the gases, which have the maximum percentage in the air?
Ans:- The gases which have the maximum percentage in the air nitrogen (78%), oxygen (21%).
(1) Explain the reaction, which takes place when potassium per magnate is heated?
Ans:- The reaction is,
2KMn04 _ K2Mn o4 + Mno2+o2
At first take about two to three gram of potassium per magnate in the thick – glassed test tube. Now heat the test tube and collect the gas formed, in a test tube which is filled with water and kept inverted. Then close the mouth of the test tube with your finger and make it stand inverted in a through filled with water. When the test tube is filled with gas, let the gas escape.
(3) What are the uses of oxygen in our daily life?
Ans:- Oxygen is very necessary in our daily life. The main use of oxygen is for respiration of plants and animals. Mountaineers’, s cube-divers, astronauts’ carry these with them in suitable cylinders. Asthma and heart patients and new born babies in hospitals having breathing problem are given oxygen masks. Mixture of oxygen and some other gases are burned to get a flame used to join metal objects.
(1) What are the main gases that pollute the air?
Ans:- The main gases that pollute the air are carbon monoxide , oxides of nitrogen, carbon dioxide.
(3) Name the gases responsible for greenhouse effect?
Ans:- The gases responsible for greenhouse effect are carbon dioxide, carbon mono oxide, methane, chloro floro carbon, ozone.
(4) Which are the gases mostly present in acid rain? How do they affect our lives?
Ans:- The gases mostly present in acid rain are sulphuric acid and nitric acid.
Acid rain is very affectively in our lives. Acid rain pollutes water sources in such a way that many species of fishes are now becoming extinct. It is also harmful for human health plant leaves turn yellow and fall off because of acid rain. It is corrodes buildings, statues specially made of stone or marble.
(1) What do you understand by atmospheric pressure?
Ans:- When the pressure applied by the atmosphere around us is called atmospheric pressure. Example when we move high above the density of the air changes and due to it the atmospheric pressure also changes. As we go up in the air, the density decreases because of the atmospheric pressure.
(2) What will happen to the human body if the air pressure of an area suddenly decreases?
Ans:- Atmospheric pressure has much effect on our body. When are go to a high altitude the atmospheric pressure decreases, due to which human our blood vessels swell up or sometimes burst.
(1) Choose the correct alternative:-
(1) Which gas has the highest percentage in air?
Ans:- (b) Nitrogen.
(2) Nitrogen is used in the storage of food items because –
Ans:- (d) It keeps the food fresh.
(3) Unit measure of atmospheric pressure is equal to the column of mercury pressure of—
Ans:- (a) 76cm.
(4) Oxygen gas as compared to water is –
Ans:- (b) Lighter.
(5) The cause of hearting up of our atmosphere is –
Ans:- (b) Greenhouse effect.
(2) Fill in the blanks:-
(1) ——-gas helps in burning.
Ans:- Oxygen.
(2) Of a nitrogen rich fertilizer—–is the main source.
Ans:- Ammonia.
(3) The atmospheric pressure—on going upwards from the earth surface.
Ans:- Swell.
(4) Acid rain is due to— and —-gases.
Ans:- Sulphur, Nitrogen oxide.
(5) Oxygen is—-in water.
Ans:- Light
(3) (1) They percentage of oxygen in air is 10 percent.
Ans:- False: The percentage of oxygen in air is 21 percent.
(2) On heating potassium permanganate we get nitrogen gas.
Ans:- False: On heating potassium permanganate we get oxygen gas.
(3) Sulphur dioxide when mixed with air pollutes it.
Ans:-True:
(4) The air pressure in the balloon is due to the air filled in it, staring the walls of the balloon.
Ans:- True.
(5) Because of the inertness of nitrogen gas it is filled in the electric bulbs.
Ans:- True:
(4) Match the following –
Green house effect:- Carbon dioxide.
Oxygen:- Perspiration.
Nitrogen:- Keeping food items fresh.
Acid rain:- Nitric acid and sulphuric acid.
(5) (1) What are the components of air?
Ans:- The components of air are nitrogen, oxygen, organ, water vapour, carbon dioxide, sulphur dioxide and other gases and dust particles.
(3) What are the causes of air pollution? What measures world you a adopt to stop it?
Ans:- Some main causes of air as follows-
(1)Vehicles:- Use of vehicles has increased day by day cars, buses, tracks, auto – rick-shaws run on petrol or diesel, which are fuels obtained from biological reactions. Because of the burning of these fuels or mostly due to the incomplete combustion of these fuels, carbon – monoxide, oxides of nitrogen, lead are liberated into the atmosphere. These gases seriously injure human health Vegetation and other objects.
(2) Industrialization:- The solid particles which are polluted. Coming out of the steel industry, cement factory, fertilizer industries have harmful effects not only on human health but also on living beings, vegetation and buildings. Increasing of population and expanding industries with increasing more energy.
Measures to adopt to stop it: (1) Change the manufacturing methods such that less quality of polluting materials is liberated.
(2) Twigs of trees paper and waste products,. Burning of day leaves must not be done in the open but disposed of in a safe manner.
(3) Tress are the lungs of nature so plant more trees.
(4) The height of the chimneys of the factories are increase then polluting gases may not accumulate at lower levels.
(4) What are the main uses of nitrogen gas?
Ans:- The main uses of nitrogen gas are
(1) Nitrogen reacts with hydrogen to from ammonia. It is used to make many as urea.
(2) Nitrogen has insert nature. So it is used in filling electric lamps to prevent oxidation of filament.
(3) Nitrogen is also used to keep stored food items fresh.
(4) Liquid Nitrogen is used as cooling agent in industry.
(5) What is acid rain? How is it harmful for us?
Ans:- When sulphur oxide and nitrogen oxide mixes with the rainwater and makes it more acidic. This is called acid rain.
Acid rain is too harmful for us. It is harms soil water resource, forests and human health. It is corrodes buildings statues specially made of stone or marble.