Some Gases || Class 9 Science Notes

SOME GASES

1. Short answer type questions:

a. What are the chemicals used to prepare hydrogen gas in the laboratory? 

= Potassium chlorate and dioxide the chemicals used to the laboratory. manganese are prepare hydrogen gas in the laboratory.

b. What is hydrogenation?

= Hydrogenation is the process in which hydrogen is passed into red not oxide to form water gas.

c. What is a catalyst? 

→ A catalyst is chemical substance used in chemical reaction to give accurate result in reaction.

d. What is the valency and atomic weight of oxygen?

= The valency of weight of oxygen is 2 and atomic weight of oxygen is 16 amu.

e. What is a chemical nitrogen? 

→ Nitrogen is an inert, non-toxic and non-metallic gas which constitudes about four-fifths of earth's atmosphere.

f. What percent of nitrogen contribute to form air? 

→ Nitrogen contributes 78.08% to form air.

g. What is ozone? Write its formula.

= Ozone is a pale blue natural gas composed of three atoms of oxygen.

 It's formula is: O₂ = O+O (Nascent Oxygen) 

                         O+O2=O3 (Ozone)

h. What is ozonosphere? 

→ Ozonosphere is a layer of atmosphere which contains a thick layer of ozone.

i. Which chemical is used to react with NH₂ CJ to produce nitrogen gas in the laboratory?

= NaNO₂ 

2. Long answer type questions.

a. Give any four precautions to be taken during the laboratory preparation of hydrogen gas.

 → The precautions to be taken during the laboratory preparation of hydrogen gas are:-

i. Impure zinc should be taken during the used because impurities in zinc act as a Concentrated sulphuric acid should not be used because it produces sulphur dioxide instead of hydrogen gas.

ii. The apparatus should be clean and made airtight.

iii. The experiment should be conducted for from fire.

b. How do you test hydrogen gas? 

 → Hydrogen burns in air with faint pale-blue a flame. When a lighter splinter is inserted in the mouth of the gas jar, the gas burns with pop sound and the splinter gets extinguished. Thus, we can say that the produced gas is hydrogen.

c. Write any three physical properties and three uses of hydrogen gas. 

→ The three physical properties of hydrogen gas are: 

i. Hydrogen is a odourless, tasteless and colourless gas. 

ii. It is almost insoluble in water. 

iii. It is neutral to litmus.

* The three uses of hydrogen gas are:-

i. It is used in manufacturing ammonia and fertilizers under certain conditions. 

ii. It is used in manufacturing vanaspati ghee by the process of hydrogenation.

iii. The liquid form of hydrogen is used rockets as fuel in

d. What property of hydrogen enables it to be collected by downward displacement of water in a gas jar? 

→ Since hydrogen gas is insoluble in water and lighter than air it is collected by downward displacement of water in a gas jar.

e. What is the role of manganese dioxide in the preparation of oxygen gas in the laboratory? 

→ Manganese dioxide increases the rate of decomposition. of potassium chlorate and hydrogen peroxide.

f. Enlist physical properties and uses of oxygen. 

→ The physical properties of oxygen:

 i. Oxygen is a odourless, tasteless and colourless gas.

ii. It is neutral to an indicator.

iii. It is slighty heavier than air. 

*The uses of of oxygen are:-

i. Oxygen is used by living beings for respiration. 

ii. It is essential for burning fuels. 

iii. Liquid oxygen is used as a fuel for rockets.

g. How do test the any you oxygen gas in a jar? Explain any one method in brief. 

→Introduce a glowing matchstick in the containing gas. If the matchstick burns with jar bright light. It proves that the gas in the jar is oxygen.

h. Give any three precautions which should be noted for the preparation of nitrogen in the laboratory.

→ The three precautions which should be anted for the preparation of nitrogen in the laboratory are:-

i. The fitted apparatus should be made airtight. 

ii. Ammonium Chloride and sodium nitrite should be taken in the equivalent amount. 

iii. The end of the delivery tube in the flask should be high close to the mouth of the flask.

i. What are the physical properties of nitrogen? 

→ The physical properties of nitrogen are:-

 i. It is slightly soluble in water. are:

ii. It is neutral to the indicator.

iii. It is generally inert, non-toxic, non-metallic, colourless, odourless and tasteless. 

j. What are the uses of nitrogen? 

= The uses of nitrogen are: 

i. It is used for manufacturing nitric acid, ammonia and calcium cyanamides.

ii. Liquid nitrogen is used in food industries as a preservative and as a refrigerant.

iii. lt is used in filling electric bulbs to produce inert atmosphere in order to prevent the oxidation of tungsten filament.

k. What is ozone? How is it formed in the atmosphere?

= Ozone is a atoms of pale blue natural gas composed of three oxygen of oxygen.

                  O+O=O2

                  O2+O=O3(Ozone Layer)

1. Suggest any four ways to conserve layer in the stratosphere.

= The four to ways Conserve the ozone layer are:-

i. The use of HCFS should be promoted instead of CFCs and HCFCS. 

ii. The use of bio-pesticides should be increased instead of chemical pesticides. use of public vehicles should be promoted.

iii. The use instead of private vehicles. A filter should be used in all vehicles to control the release of greenhouses.

iv. The Use of gases in the atmosphere of nitrogenous fertilizers should be reduced and the gradual replacement of such fertilizers by organic fertilizers should be promoted.

m. Write the importance of the ozone existence of life on the earth.

= The importance of the ozone existence of life on the earth are:-

i. The ozone layer for the layer for the the earth are layer plays a significant role in the balance of weather and temperature on the earth.

ii. The ozone layer helps to regulate and the terrestrial as well as aquatic ecosystem of the nature.

iii. The ozone layer protects human beings and other animals from various diseases likely to be caused by UV radiations.

3. Give Reasons:

a. Concentracted H₂SO4 cannot be used instead of dilute H₂SO, in the laboratory preparation of hydrogen gas. 

= Concentracted H₂SO4 cannot be used instead of dilute H₂SO, in the laboratory preparation of hydrogen gas Because it will produce sulphur dioxide as instead of hydrogen.

b. Hydrogen gas is gathered by downward displacement of water.

→ Hydrogen gas is collected by downward displacement of water Because hydrogen is insouble in water.

c.  Unadulterated zinc is not used in laboratory preparation of Hydrogen?

= Unadulterated zinc isn't utilized in the research facility planning of hydrogen gas since it is non-permeable.

d. Unadulterated hydrogen gas isn't utilized in ballons.

→ Pure hydrogen gas is not used in ballons Because hydrogen is lighter than air but it is flamable and as oxygen is present the air so risk of explosion and fire is there.

e. Oxygen is involved by living creatures for breath.

= Oxygen is used by living organisms for respiration Because oxygen we inhale is used to breakdown glucose into carbon dioxide and water.

f. The mouth of a hard glass test the tube is slightly slanted during preparation of oxygen gas. 

→ The mouth of a hard glass test the tube is slightly slanted during preparation of oxygen gas Because to prevent the glass tube from cracking due to back flow of water from water trough!

g. Hydrogen and oxygen can be collected by electrolysis of water.

→ Hydrogen and oxygen can be collected by electrolysis of water Because electroysis of water is the splitting of the water molecular hydrogen and oxygen.

h. Ozone forms a protective layer around the earth's atmosphere.

→ Ozone forms a protective layer around the earth's atmosphere Because Ozone layer is good at trapping UV radiation which harms organisms skins.

j. Nitrogen gas is filled in an electric bulb.

→ Nitrogen gas is filled in an electric bulb Because it doesnot react with the bat filament

k. Nitrogen gas is collected by download displacement of water? 

= Nitrogen gas is collected by download displacement of water Because the any gas be collected by this method and gas pushes the water down as it is lighter and do not react with water.

n. What happens while consuming charcoal is kept in a gas container containing oxygen?

→ When burning charcoal is kept in a gas jar containing oxygen then carbon dioxide is formed.

o. A burning candle, when brought near the mouth of a gas jar containing hydrogen, starts with a sound but it is extinguished when inserted" inside the jar. Why?

= A burning candle, when brought near the mouth of a gas jar containing hydrogen starts with a pop sound but it is extinguished when inserted inside the jar because the consuming requires the presence of oxygen which is absent inside the container.

p. What happens when inserted in a a burning magnesium ribbon is a jar containing nitrogen gas? Also, write the chemical equation." 

= When a burning magnesium ribbon is inserted a jar containing nitrogen gas, it generate solid magnesium nitride. The chemical equation is;

q. What are the causes of the layer ozone depletion? How do CFCs deplete the ozone? Explain with chemical equations. 

→ The causes of the ozone layer depletion are:

i. Chlorofluorocarbons (CFCs)

ii. Unregulated Rocket Launches

iii. Nitrogenous Compounds.

iv. Natural Causes 

* CFCs deplete the ozone when (CFC) drift upwards. towards the stratosphere, they the ozone came in contact with layer. This leads to a chemical reaction where the CFC molecules are broken up by ultravoilet radiation, releasing chlorine atoms, which are able to destroy molecules. The chemical equation is CL+O3===CLO+O2.

r. How would We realize about the huge measure of UV beams arriving at a specific piece of the earth?

→ Everyone is exposed to UV radation from the sun and an increasing number of people are to artificial sources used in industry, commerce and recreation. The sun is by far the strongest source of UV radiation in our environment. Solar emissions include visible light, heat and UV radiation. Just as visible light consists of different colours that become apparent in a rainbow, the UV radiation spectrum is divided into three regions called UVA, UVB and UVC and most UVB is absorbed by ozone, water vapour, carbon dioxide and oxygen.

s. "The main causes of ozone layer depletion? How do are the activities of human beings. Clarify this statement.

= "The main Causes of ozone layer depletion are the activities of human beings " this statement is correct because human beings runs industries, factories, etc. which produce so much harmful gases towards the environment and harmful gases goes upwards to the atmosphere. it deplete the ozone layer.