1- What is atmosphere?
Ans:- Atmosphere is the thin layer of air that surrounds the earth. It is made up of various gases such as oxygen, nitrogen, carbon dioxide, dust particles and water vapour. It protects us from harmful rays and scorching heat of the sun.
2- How many layers of atmosphere?
Ans:- There are five layers of atmosphere
1- troposphere
2- stratosphere
3- mesosphere
4- thermosphere
5- exosphere
3- What is troposphere?
Ans:- The lower layer of the atmosphere is called the troposphere. It is spreaded up to 10 km above the earth. The formation of cloud and the weather changes take place in troposphere. As we go higher in the troposphere, air becomes thinner and breathing becomes difficult.
4- Why do the climbers of mount Everest take air cylinders with them ?
Ans:- As we go higher on the mount Everest, air becomes thinner and breathing becomes difficult. There for the climbers of mount Everest take air cylinders with them.
what is stratosphere
The layer of atmosphere that is found just above the troposphere is called stratosphere. It extends from about 10km to 50 km above the earth. There is very little air in this layer, therefor jet aeroplanes fly in this layer. The stratosphere contains a layer of ozone gas which protects us from harmful ultravoilet ray of the sun.
What is mesosphere?
The layer of atmosphere that is found just above the stratosphere is called mesosphere. It extends from about 50km to 80km above the earth. The temperature of atmosphere decreases with increasing in altitude.
What is thermosphere?
The layer of atmosphere that is found just above the mesosphere is called thermosphere. It extends from 90km to 500km. Artificial satellites orbit in this region.
What is exosphere?
The layer of atmosphere that is found just above the thermosphere is called exosphere. It is the outermost layer of atmosphere. It extends from 500km to 1000km. It has very thin layer of air.
How does the atmosphere protect us?
Atmosphere protects us by following ways
1- It has oxygen which we use to breathe.
2- It has carbon dioxide which plants use to make food.
3- It protects us from extreme heat of sun by stoping the large part of heat of sun.
4- It protects us from extreme cold by stop the heat of earth from escaping out into space.
5- Atmosphere contains a layer of ozone gas which protects us from harmful ultravoilet ray of the sun.
Write short notes on composition of air
Air has 78 % of nitrogen, 21 % of carbon dioxide and only 1% of other gases like argon, carbon dioxide etc. There is only 0.03 % of carbon dioxide in air. More than three-fourth parts of air is nitrogen. About one-fifth part of air is oxygen.
What is humidity?
Ans:- The amount of water vapour in the air is called humidity.
Chennai has more humidity in the air than Delhi. Why?
Ans:- Chennai has more humidity in the air than Delhi because Chennai is situated near the sea. There is a lot of evaporation of sea due to the heat of sun. This increase the humidity in the air of Chennai.
Write six properties of air.
Ans:- The six properties of air are
1- Air occupies space.
2- Air has mass.
3- Air has no definite mass .
4- Air has no definite volume.
5- Air is colourless.
6- Air exerts pressure.
Write short notes on appearance of water on earth
Ans:- 71 % of earth is covered with water, about 97% of this water is present in the oceans or seas. 2% of water is present in the form of ice in glaciers. Only 1% of water is available as fresh water for drinking.
How many kinds of impurities present in water?
There are two kinds of impurities present in water.
1- Soluble impurities
2- insoluble impurities
What are soluble impurities of water? Write example.
Ans:- Those impurities that are soluble in water are called soluble impurities.
Ex:- salt , minerals etc.
What are insoluble impurities of water? Write example.
Ans:- Those impurities that are not soluble in water are called insoluble impurities.
Ex:- stone, sand, mud, chalk etc.
How can we remove insoluble impurities from water?
Ans:- We can remove insoluble impurities from water by two ways
1- By sedimentation and decantation
2- By filtration
What is sedimentation?
Ans:- The process of settling down of the heavier particles present in a liquid mixture is called sedimentation.
What is decantation?
Ans:- pouring out of upper clear layer of liquid into another container to separate two immiscible liquids is called decantation.
What is filtration?
Ans:- Filtration is a physical process by which the solid particles are separated from liquids using a filter as a medium that retains solid particles and let the liquid to pass through the filter.
What is evaporation?
Ans:- The changing of a liquid into gas is called evaporation. Evaporation is used to obtain a solid substance that has dissolved in water or any other liquid. The dissolved substance is left as a solid residue when all the water has evaporated.
What is distillation?
Ans:- Distillation is the process of heating water to form water vapour and than cooling the hot water vapour to get back liquid water.
Ex:- Alcoholic beverages are made through distillation.
Salt water is turned into fresh water through distillation.
Write some uses of distillation.
Ans:- Some uses of distillation are
1- It is used to separate two liquids which have different boiling point.
2- It is used to separate liquids from nonvolatile solids.
Write two ways to purifying drinking water and explain.
Ans:- The two ways to purifying drinking water are boiling and chlorination.
Boiling - Boiling is the simplest way to purifying water. boil the water for 10 minutes to purify. this will kill the germs and make it safe for drinking.
Chlorination - Chlorination is a method to purifying water by adding chlorine. Chlorine is added to water which kills germs and make the water pure.
List the steps involved in cleaning water for supply in a town.
Ans:- The steps involved in cleaning water for supply in a town are sedimentation, filtration and chlorination.
Sedimentation - In step one, Water from river or lake is collected in huge tank and allowed to stand. This helps the heavier particles of insoluble impurities settle down.
filtration - In step two, The water than passes through filters made of chemicals, sand and gravel to remove fine particles of insoluble impurities.
Chlorination -
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