Some Gases: Class 10 Science Notes

Some Gases Class 10 Science Complete Notes. This note include all the excercise given in Some Gases chapter of science book such as question answer, numericals, give reason, diagrammatic questions and define the following. This note is published for helping students to solve their problems.

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  Chapter - 10  
Some Gases

2. Give Reason :

a. Ammonia is not collected through downward displacement of water.

Ans: Ammonia is not collected through downward displacement of water because ammonia is lighter than air and it is highly soluble in water.

b. Ammonia is collected by the downward displacement of air.

Ans: Ammonia is collected by the downward displacement of air because it is highly soluble in water and it is also lighter than air.

c. Carbon dioxide is used in a fire extinguisher.

Ans: Carbon dioxide is used in a fire extinguisher because carbon dioxide is a non-combustile gas and it does not support burning.

d. H₂SO₄ is not used in the Preparation of Co₂.

Ans: H₂SO₄ is not used in the preparation of Co₂ because calcium sulphate produced during reaction covers the remaining part of the marble and does not allow further reaction as calcium sulphat is insouble in nature.

e. The opening of hard glass test tube is slanted down during laboratory preparation of ammonia gas.

Ans: The opening of hard glass test tube is slanted down during laboratory preparation of ammonia gas because to prevent the glass from cracking.

f. Carbon dioxide does not support in burning but Mg burns in it.

Ans: Carbon dioxide does not support in burning but Mg burns in it because the oxygen atom present in carbon dioxide is able to bond with magnesium and produce an oxide. 

3. Answer the following questions:

a. What are the uses of Carbon dioxide ?

b. Write any four physical properties of carbon dioxide.

c. Give the formulae and the chemical names of slaked line, lime stone and urea.

d. How will you show that carbon dioxide is heavier than air.

Ans: If we fill carbon dioxide in a balloon then it remains on the surface of the earth which proves that carbon dioxide is heavier than air.

e. What is meant by dry ice? What is it used for.

Ans: The ice obtained from cooling CO₂ gas at about -78°C is called dry ice. It is used to preserve fruits and vegetables as it works as rebrigerant.

f. How do you test whether the gas is carbon dioxid or not? 

Ans: When a burning match stick is put near the jar Containing CO₂ a pop sound is heard which indicates the carbon dioxide.

g. What happens when carbon dioxide is passed into lime water for a short time? Give the equation as well. 

Ans: When Carbon dioxide is passed into lime water for a short time then calcium carbonate is formed.
Ca(OH)₂ + CO₂ → CaCo₃ + H₂O

h. Explain the following with the help of a chemical equation.

Ans: Because the high temperature of burning magnesium breaks Co₂ into carbon and oxygen. So, oxygen formed supports burning.
2mg + Co₂ → 2MgO + C

ii. Milky colours disappear's when excess of carbon dioxide, is passed through lime water.

Ans: Milky colours disappears when excess of carbon dioxide is passed through lime water due do the formation of water soluble calcium carbonate
CaCO₃+ CO₂ + H₂O → Ca(HCO₃)₂

i. What is meant by photosynthesis? Give the chemical reaction involved in it.

Ans: The process of making food by plants with the help of sunlight is known as Photosynthesis. 
Reaction
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

j. How is carbon dioxide collected in laboratory?

Ans: Carbon dioxide is collected in laboratory by the upward displacement of air.

k. What happens to moist blue litmus paper when it is dipped into carbon dioxide? Give reason.

Ans: When moist blue litmus paper is dipped into carbon dioxide, it turns into red because carbon dioxide is acidic in nature.

l. Which gas is produced when lime stone reacts will hydrochloric acid? Write the balanced equation. What happens when this gas is passed in lime water for some time.

Ans: When lime stone reacts with hydrochloric acid then Carbon dioxide gas is produced.
CaCO₃ + 2HCl → CaCl₂+ H₂O + CO₂ 
When Co₂ is passed in lime water for some then calcium carbonate is formed.

m. Write a chemical equation involved in the laboratory Preparation of ammonia?

Ans: Ammonium chloride + calcium hydroxide → calcium chloride + water + ammonia
2 NH₄Cl + Ca(OH)₂ → CaCl₂ + 2H₂O + 2NH₃

n. What are the necessary conditions for the manufacture of ammonia by Haber's process? Give the balanced equation as well.

Ans: The necessary conditions for the manufacture of ammonia by Haber's process are as follows:

• Temperature of about 500°C should be maintained
• High pressure of about 200-900 atmosphere should be maintained 
• Iron should be used as catalyst 
• Traces of molybdenum as a promoter 
• High Concentration of reactants

Equation
N₂ + 3H₂ → 2NH₃

o. What are the physical properties of ammonia.

Ans: The physical properties of ammonia are as follows:

• It is highly soluble in water
• It is lighter than air
• It is a colourless gas
• It is neither combustile nor supporter of a combustion

p. Ammonia turns red litmus into blue. What does it show?

Ans: Ammonia turns red litmus into blue. It shows that ammonia is basic in nature.

q. How can you prepare ammonium sulphate from ammonia?

Ans: We can prepare ammonium sulphate from ammonia by the chemical reaction between ammonia and sulphuric acid. 
2NH₃ + 2H₂So₄ → (NH₄)₂So₄ 

r. What type of litmus can help to confirm that a gas is filled with ammonia?

Ans: Red litmus can help us to confirm that a gas is filled with ammonia as it changes into blue.

s. What is meant by liquor ammonia? Write any four uses of ammonia.

Ans: Liquor ammonia is a strong ammonia solution. The four uses of ammonia are as follows:

• It is used to manufacture chemical fertilizers
• It is used for developing blue print of maps 
• It is used to manufacture washing soda
• Its solution is used as laboratory reagent

4. Diagrammatic questions:

a. Draw a neat and labelled diagram for the preparation of carbon dioxide in laboratory. Give the balance equation of chemical reaction involved in it

Reaction 
Calcium Carbonate + dil. Hydrochloric acid → Calcium Chloride + water + Carbon dioxide
CaCO₃ + 2HCl → CaCl₂+ H₂O + CO₂ 

b. Study the given diagram and answer the questions below:

i. Find the mistake in the apparatus set up in the given diagram.

Ans: In the apparatus, thistel funnel should be dip in CaCO₃  and delivery tube shouldn't be dipped in CaCO₃ .

ii. Which gas is being produced? Write the balanced Chemical equation of the reaction. Write its one use

Ans: Carbon dioxide gas is being produced in the abov reaction.
CaCO₃ + 2HCl → CaCl₂+ H₂O + CO₂ 
One use of Carbon dioxide is given below:
It is used to manufacture soft drinks

c. Study the given figure and answer the following questions.

i. Which gas is collected in the gas jar ?
Ans: Ammonia gas is being collected in the gas jar.

ii. Write the balanced chemical equation involved in the process.
Ans: 2 NH₄Cl + Ca(OH)₂ → CaCl₂ + 2H₂O + 2NH₃

iii. What will happen it quick lime is replaced in drying tower by Conc.H₂So₄
Ans: If quick lime is replaced in drying tower by conc. H₂So₄ then they will reaction with each other and ammonium sulphate will formed

2NH³ + H²SO⁴ → (NH₄)₂SO₄

iv. Name the compound formed in the jar is moist.
Ans: If the gas jar is moist the compound formed is liquor ammonia

NH³ + H²O → NH⁴OH

5. Complete the given reactions and balance them.

a. CO₂ + H₂O → H₂CO₃

b. Ca(HCO₃)₂ + 2HCL → CaCl₂ + 2H₂O + 2CO₂

c. CaCO₃  → CaO + CO₂ 

d. 2NH₃ + Co₂ → NH₂-CO-NH₂ + H₂O

e. NH₃ + HNO₃ → NH₄NO₃

f. NH₃  + H₂So₄ →  (NH₄)₂So₄ 

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