CBSE Class 10 Science Important Questions Chapter 4 Carbon and Its Compounds Part 2

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2 Marks Questions

1. Name the following compounds.

(a)

Compounds

Compounds

(b)

Ans. (a) Methanol

(b) Chloroethane

2. Define soaps?

Ans. Soaps are the sodium or potassium salts of long chain fatty acids. These are represented by RCOONa or RCOOR.

3. Name the second member of alkynes family Give its structure? Ans. The second member of the alkyne family is propyne. Its structural formula is

4. Give a chemical test to distinguish between Ethane and ethene.

Ans. Ethene decolorizes the yellow colour of bromine water while ethane does not.

5. Write the structures of

(i) Ethanoic acid

(ii) Hex anal

Ans. (i)

Structures

Structures

(ii)

Structures

Structures

6. Name the following compounds

a.

b.

Ans. (a) Ethanal

(b) Ethanol

7. Which organic compound is added to make ethanol unfit for drinking purposes? What is the name of the mixture formed?

Ans. Methanol which is highly poisonous is added to make ethanol unfit for drinking purpose. The mixture is called methylated spirit or denatured alcohol.

8. Write a test to identify the presence of Ethanoic acid?

Ans. Dip a strip of blue litmus paper in the solution of Ethanoic acid. Its colour will change to red.

9. What are the properties of carbon which lead to huge number of carbon compounds we see around us?

Ans. (i) Self linking property called catenation

(ii) Carbon is tetravalent and can readily unite with atoms like hydrogen, oxygen etc by electron sharing

10. Name the following compound

(a)

(b)

Ans. (i) Bromoethane

(ii) Hex-1- yne

11. Why conversion of ethanol into Ethanoic acid is an oxidation reaction?

Ans. Ethanoic acid has one, atom more and two hydrogen atoms less then ethanol. And loss of hydrogen is known as oxidation and gain of oxygen is known as oxidation. Therefore it is an oxidation reaction.

12. A mixture of ethyne and oxygen is used for welding. Can you justify why a mixture of ethyne and air is not-used?

Ans. When ethyne is burnt in oxygen, large quantity of heat and light is produced. The heat evolved can be used for gas welding which is used for welding broken pieces of articles. As air contains mixture of nitrogen and oxygen and nitrogen which is more in amount does not support combustion. Therefore, it is always better to use oxygen for the combustion of ethyne.

13. Why carbon and its compounds are used as fuels in most cases?

Ans. Carbon burns in oxygen or air to form gas. This reaction is highly exothermic that is why different form of coals are used as fuels

14. A compound X has the molecular formula with structural formula. Give its IUPAC name. Can another compound have the same molecular formula? Give the structure and IUPAC name of that compound also.

Ans. The IUPAC name of X is propanal.

Another similar compound is Y is.

Propanone

Propanone

X and Y are related to each other as functional isomers.

15. Why CHO group cannot be present in the middle of the carbon atom chain?

Ans.The CHO group is a terminal functional group since three valencies of the C-atom are already satisfied, so this group cannot be present in the middle of the chain.

16. Two carbon atoms cannot be linked to each other by more than three covalent bonds. Why?

Ans. When two carbon atoms are to linked by four covalent bonds their nuclei come so close to one another that the force of repulsion between them will push these apart. As a result, a stable molecule will not be formed.

17. What would be the electron dot structure of carbon dioxide which has the formula of

Ans.

Electron dot structure of carbon dioxide

Electron Dot Structure of Carbon Dioxide

18. What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur?

Ans.

The electron dot structure of a molecule of sulphur

The Electron Dot Structure of a Molecule of Sulphur

19. How would you name the following compounds?

Compounds

Compounds

Ans. (i) Bromomethane

(ii) Hexyne

20. What are two properties of carbon which lead to the huge number of carbon compounds we see around us?

Ans.The two properties are:

(a) catenation- the ability to form bonds with other atoms of carbon. (b) Tetravalency of carbon.

21. Would you be able to check if water is hard by using a detergent? Ans. No, we would be able to check if water is hard by using a detergent

22. People use a variety of methods to wash clothes. Usually after adding the soap, they beat the clothes on stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?

Ans. Agitation is necessary to obtain complete me cells formation and the emulsion of oil in water so that the whole of dirt is removed on rinsing with water.

23. Explain the nature of the covalent bond using the bond formation in.

Ans. Covalent bond is formed by sharing of electrons between two atoms. It is non-ionic in nature.

Covalent bond

Covalent Bond

24. Give a test that can be used to differentiate chemically between butter and cooking oil?

Ans. Butter and cooking oil can be differentiated with the help of bromine water test. Cooking oil will decolorize the red colour of bromine water on shaking while butter will not.

25. A compound ‘X’ ha molecular formula. It undergoes substitution reaction readily than addition reaction. It burns with blue flame and is present in LPG. Identify ‘X’ and give the balanced equation for its combustion and substitution reaction with in presence of sunlight.

Ans.

26. ‘A’ compound works well with hard water. It is used for making shampoos & products for cleaning clothes. A is not 100% biodegradable and causes water pollution. ‘B’ does not work well with hard water. It is 100% biodegradable and does not create water pollution. Identify A & B.

Ans. A is detergent & B is soap.

27. An organic compound P with molecular formula C2H6O is an active ingredient of all alcoholic drinks. It is also used in medicines such as tincture iodine, cough syrup. 1 dent if ‘P’. Drop a small piece of sodium into the test tube containing ‘P’.A new

Compound ‘Q’ is formed with the evaluation of colourless and odourless gas Name the gas evolved and compound ‘Q’ write the chemical reaction.

Ans.

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