Class 10 Science Chapter 4 Board Questions

Class 10 Science Chapter 4 Board Questions of Carbon and its Compounds are given below. This page includes all the questions related to last ten years CBSE papers and CBSE sample papers from chapter 4 of class 10 science for the preparation of CBSE Exams 2020-21.

Question and answers of last 5 years’ board papers with complete explanation are given at one place.

Class 10 Science Chapter 4 Board Questions Answers

Class: 10Science
Contents:Chapter 4: Board Questions

Class 10 Science Chapter 4 Board Questions for 2020-21

Class 10 Science Chapter 4 Board Questions divided into sets of one mark, two marks, three marks and five marks questions. Answers of 1 mark questions are given in one word or one sentence, 2, 3 or 5 marks questions are also answered properly point wise. CBSE Board year is also mentioned in front of each question.

10th Science Chapter 4 Board Questions Set – 1 (1 Mark)

Give the name of the following functional groups: (i) –OH (ii)-COOH [CBSE 2007]

(i) Alcoholic group.
(ii) Carboxylic group.

Name the fourth member of the alkaline series. [CBSE 2011]

Fourth member is pentane (C5H10).

Name an element other carbon which exhibits the property of catenation upto seven or eight atoms Are these compound stable? [CBSE 2012]

Silicon also exhibits the property of catenation. Compound of silicon are not stable.

List two characteristic feature of carbon are which when put together give rise to a number of carbon compound. [CBSE 2013]

The two features are: Catenation and tetra-valency.

Write the name and the molecular formula of an alkyne having four carbon atoms. [CBSE 2013]

Butyne (C4H6)

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10th Science Chapter 4 Board Questions Set – 2 (1 Mark)

Name the substance used for oxidation of ethanol and the compound formed an oxidation. [CBSE 2013]

Alkaline KMno4 or acidified K2Cr2O7 is used for oxidation of ethanol. Ethanoic acid is formed on oxidation.

“Carbon tetrachloride is not a good conductor of electricity”. Give reason to justify the statement. [CBSE 2013]

Carbon tetrachloride is a covalent compound. Such compound does not produced ions. Therefore, carbon tetrachloride is not a good conductor of electricity.

Apart from organic beings whereas do we find carbon? Mentions the forms in which it is available there and also its percentage. [CBSE 2013]

Carbon is found in the atmosphere and earth’s crust. In the atmosphere it is found as CO2 and in the earth’s crust it is found as mineral like carbonates.
The percentage of carbon in the air is 0.03% and in the earth crust it is present to the extent of 0.02%.

Write the number of covalent bond in the molecule of ethane. [CBSE 2015]

Seven covalent bond.

Write the name and formula of the 2nd member of homologous series having general formula CH2n. [CBSE 2015]

Compound with the formula CH2 does not exist.
First member of the series is C2H4(Ethene)
Second member of the series is C3H6(Propene)

The Catenation Property

The unique property of carbon to form bonds with other carbon atom giving rise to large molecules is called catenation. Due to catenation compound of carbon have long chain of carbon branched chain of carbon even carbon atom arranged in rings.

10th Science Chapter 4 Board Questions Set – 3 (1 Mark)

Write the next homologous of each of the following: (i) C2H4 (ii) C4H6 [CBSE 2016]

(i) C3H6 Propene
(ii) C5H8 Pentyne

Write the molecular formula of (i) methane (ii) ethanol [CBSE2017]

Methane: CH4
Ethanol: C2H5OH

Which type of compound can be formed by carbon? [CBSE 2018]

Covalent compound.

Why does only carbon exhibit property of catenation and form large number of compounds with other elements? [CBSE 2012]

Carbon atom has a small size and this enables its nucleus to hold on the shared pair of electron quite strongly. This is why carbon forms strong bond with most other elements and the compounds formed are exceptionally stable as compared to covalent bond formed by other elements.

Write the name of the saturated hydrocarbon having two carbon atom. Also write its chemical formula. [CBSE 2012]

Saturated hydrocarbon having to carbon atom is ethane. Its chemical formula is C2H6

Discussion Forum is being maintained in such a way that every student can asked his doubts. Everyone is allowed here to asked questions or reply to the questions already asked.

10th Science Chapter 4 Board Questions Set – 4 (1 Mark)

Name any other elements which like carbon can form compounds which have chains upto seven or eight atoms. How do these compound differ from carbon compound? [CBSE 2012]

Silicon forms compound which have chains like carbon. Compound formed by silicon are few and
are not so reactive.

Name the functional group present in the following compound: (i) CH3COOH (ii) CH3COCH3 [CBSE 2012]

(i) Carboxylic acid group
(ii) Ketonic group

Write two member of the homologous series given below: C2H6, C3H8 [CBSE 2012]

C4H10, C5H12

Define isomerism. [CBSE 2011]

The phenomenon in which two or more compounds having same molecular formula may exist with different structural formulae is called isomerism.

Explain saponification? [CBSE 2011]

The reaction of an esters to react with an acid or base to give back the alcohol and carboxylic acid is called saponification. This is so called because this reaction is used in the preparation of soap.

Isomers

The compound that contain the same molecular formula but different structures are called structural isomers. The isomers of a compound have different physical properties. For example, butane with molecular formula, C4H10.

10th Science Chapter 4 Board Questions Set – 5 (3 Marks)

How would you name the following compounds? (i) CH3CH2CH2- C(CH3)2-CH3 (ii) CH3CH2CHO (iii) CH3CH(OH)CH3 [CBSE 2012]

(i) CH3CH2CH2- C(CH3)2-CH3
2,2-Dimethylpentane

(ii) CH3CH2CHO
Propanal

(iii) CH3CH(OH)CH3
2-Propanol

Specify any three rules of nomenclature of organic compounds. [CBSE 2013]

(i) Count the number of carbon atoms in the compound and give it the base name accordingly.
(ii) Identifying the functional group in the compound and name the compound by adding the prefix or suffix to the base name.
(iii) If there are only carbon atom single bonds, the ending in the base name will be ‘ane’. If there are double or triple bonds the ending in the base name will be ‘ene’ and ‘yne’ respectively.

Give two example of covalent bond compound which you have studied. State any four properties in which covalent compound differ from ionic compounds. [CBSE 2013]

Ethanol and ethanoic acid are example of covalent compound.
Difference in properties of covalent and ionic compounds:
(i) Covalent compounds are formed by sharing of electron while ionic compounds are obtained by transfer of electrons.
(ii) Covalent compound do not conduct electricity while ionic compound do.
(iii) There are weaker intermolecular forces in covalent compound compared to ionic compounds.
(iv) Covalent compounds possess lower melting and boiling point compared to ionic compounds.

A mixture of ethyne and oxygen is burnt for welding. In your opinion why cannot we use a mixture of ethyne and air for this purpose? [CBSE 2015]

A mixture of ethyne and oxygen undergoes complete combustion and high temperature is attained suitable for welding. Whereas air is mixture of nitrogen and oxygen. Oxygen can burn ethyne into carbon dioxide and water with the production of heat. Nitrogen does not have the property of burning ethyne. Therefore, less heat will be produced if we burn ethyne and air for welding purposes.

10th Science Chapter 4 Board Questions Set – 6 (3 Marks)

With the help of an example explain the process of hydrogenation. Mention the essential conditions for the reaction and state the change in physical properties with the formation of the product. [CBSE 2015]

Conversion of an oil into fat by passing hydrogen gas in the presence of nickel as catalyst is called hydrogenation. This is how hydrogenation is carried out.
Conditions: Presence of a catalyst like nickel is essential.
Change in physical properties: Oils are liquid while the fats obtained on hydrogenation are solid that’s why a physical state take place on hydrogenation.

What is the difference between the molecules of soap and detergents chemically? Explain the cleaning action of soaps. [CBSE 2015]

Soap are sodium or potassium salt of long chain carboxylic acids.
Detergents are ammonium and sulphonate salt of long chain carboxylic acids.
Cleaning action of soap: The ionic end of soap dissolves in water while the carbon chain dissolves in oil. Soap molecules form micelle where one end of the soap molecule is linked to the oil droplet while the ionic part faces water. This form an emulsification in water. On adding water this micelles containing dirt are washed away and our clothes are washed clean.

List two tests for the experimentally distinguish between an alcohol and carboxylic acid and describe how these tests are performed. [CBSE 2015]

Test 1: Reaction with sodium: Two one ml of the sample in a test tube. Add a small dried pieces of sodium metal into it. If bubbles of hydrogen are seen the sample is alcohol otherwise it is a carboxylic acid. Hydrogen gas burns with pop sound. When a flame is brought near it.

Test 2: Reaction with sodium hydrogen carbonate: Take 2 ml of saturated liquid solution of sodium hydrogen carbonate in a test tube. Add a little of the unknown sample into it and shake. If evolution of carbon dioxide gas take place, then the sample is carboxylic acid otherwise it is an alcohol. Carbon dioxide when pass through lime water turns milky.

Write chemical equation of the reaction of the ethanoic acid with the following: (i) Sodium (ii) Sodium hydroxide (iii) Ethanol [CBSE 2016]

(a) 2Na + 2CH3COOH → 2CH3COONa + H2

(b) NaOH + CH3COOH → CH3COONa + H2

(c) C2H5OH + CH3COH → CH3COOC2H5 + H2

10th Science Chapter 4 Board Questions Set – 7 (3 Marks)
What are covalent compounds? Why are they different from ionic compounds? List their three characteristic properties. [CBSE 2016]

Covalent compounds are the compounds that contain covalent bonds in the molecule. A covalent bond is formed by sharing of electron between atoms.
While a covalent compound contains covalent bond the ionic compound is made up of ionic bond which is formed by the transfer of electrons from one atom to the other.
Characteristics of covalent compounds:
(i) These compound show low melting and boiling point because the intermolecular forces are weak.
(ii) Such compounds are poor conductor of electricity.
(iii) Generally insoluble or less soluble in water but soluble in organic solvents.

When ethanol reacts with ethanoic acid in the presence of conc. H2SO4, a substance with fruity smell is produced. Answer the following: (i) State the class of compound to which the fruity smelling compounds belong. Write the chemical reaction for the equation and the chemical name of the product. (ii) State the role of conc. 2SO4 in this reaction. [CBSE 2016]

(i) Fruity smelling compounds belong to the class of ester.
C2H5OH + CH3COOH → CH3COOC2H5 + H2O
(ii) Conc. H2SO4 acts as a dehydrating agent and removing the water formed in the reaction.

What is homologous series of carbon compound? List its any two characteristics. Write the name and formula of next higher homologous of HCOOH. [CBSE 2017]

A series of compound whose two successive member differ by –CH2 in the molecule formula and which shows similar chemical properties are called homologous series.
Characteristics:
1. Melting and boiling points increase regularly with increase in molecular mass.
2. Solubility in a particular solvent shows a regular gradation.
3. Chemical properties remain the same in homologous series.
Next higher homologue of HCOOH is CH3COOH. Its name is ethanoic acid or acetic acid.

Why do carbon form largest numbers of compounds? Give two reasons. [CBSE 2012]

Carbon has two unique features:
(i) It is tetravalent.
(ii) It has the property of catenation.
The above two feature enables carbon to form a large numbers of compounds with varying size, shape that’s why carbon atom has long chain or even are arranged in branches or rings. Because of tetra-valency carbon atom in its compound are linked by single, double or triple bonds. Carbon atom are also bonded with oxygen, hydrogen, chlorine, nitrogen and sulphur giving rise to compounds with specific properties typical of the element other than carbon present in the molecule.

10th Science Chapter 4 Board Questions Set – 8 (3 Marks)
Differentiate between saturated and unsaturated hydrocarbon giving one example each. [CBSE 2012]

Saturated hydrocarbons:
A hydrocarbon in which each carbon atom is attached to four other atoms is known as saturated hydrocarbon. The bonds so formed are single covalent bonds. These hydrocarbons are also called alkanes.
Unsaturated hydrocarbons:
Hydrogens containing either a carbon double bond (C=C) or a carbon-carbon triple bond in their molecules are called unsaturated hydrocarbon.

(a) What are hydrocarbons? Give one example. (b) Mention the structural difference between saturated and unsaturated hydrocarbons. Write two example each. [CBSE 2012]

(a) Compound containing carbon and hydrogen are called hydrocarbon example methane (CH4).
(b) Structural difference- Saturated hydrocarbon have all its carbon connected to each other by only single bond whereas in unsaturated hydrocarbons there are one or more double or triple bonds between two carbon atoms.
Saturated hydrocarbon- methane (CH4), ethane (C2H6).
Unsaturated hydrocarbon- ethene (C2H4), ehyne (C2H2).

Define homologous series of carbon compounds. List any two characteristic of a homologous series. [CBSE 2012]

A homologous series in a group or family of compounds which contain the same functional group but have different chains lengths thus these have the same chemical properties but different physical properties but different physical properties that vary in a regular manner.
Characteristics of homologous series are:
(i) It has a general formula in term of number of carbon atoms.
(ii) It has the functional group if any,
(iii) The member of a homologous series that’s why homologous have similar chemical properties.
(iv) Various homologous can be prepared by the general method of preparation for the series.
(v) Two successive (adjacent) homologous differ by 1 carbon atom and 2 hydrogen atoms in their molecular formulae.
(vi) The members of a homologous series show a gradual change in their physical properties with increases in molecular mass.

Both soap and detergent are some type of salts. What is the difference between them? Describe in brief the cleansing action of soap. Why do soaps not form lather in hard water? List two problems that arise due to the use of detergents instead of soaps. [CBSE 2015]

Soaps are sodium or potassium salts of long chain fatty acids while detergents are ammonium or sulphonate salts of long chain carboxylic acids.
Soaps molecules has two parts. The ionic end of soap dissolves in water while the carbon chain dissolves in oil. Most dirt is oily in nature. Soap molecules form a micelle around dirt (oil) whose outer parts are directed towards water. On adding excess water, the dirt along with the soap molecules is washed away. This is how the cleansing action of soaps is described. Hard water contains chlorides and sulphates of calcium and magnesium which react with soap to form insoluble scum. Therefore, soap is not able to perform its cleansing action.
Detergents are not biodegradable substances. Thus, they may cause water pollution. Detergents are highly basic in nature. They may affect the skin.

Following questions contains five marks each. Answers are given point wise. If you have any doubt, first solve using NCERT Books otherwise please visit to discussion forum and ask your doubts.

10th Science Chapter 4 Board Questions Set – 9 (5 Marks)
(a) Give reasons for the following: (i) Unsaturated hydrocarbons show addiction reaction. (ii) Conservation of ethanol to ethanoic acid is an oxidation reaction. (iii) Alcohol supplied for industrial purpose is mixed with copper sulphate. (b) Write chemical equation to represent the preparation of ethane from ethanol. (c) State the role of concentrated sulphuric acid in an esterification reaction. [CBSE 2013]

(a)
(i) Unsaturated hydrocarbons show addition reaction. This is because unsaturated hydrocarbon contains double or triple bonds. Such compounds are unstable because the four valences of carbon atom are not satisfied by linking to four atoms. They complete the four valences in addition reaction.
(ii) In the conversion of ethanol to ethanoic acid, the number of oxygen atoms increases and the number of hydrogen atoms decreases. Hence, it is an oxidation reaction.
(iii) Alcohol supplied for industrial purpose is cheap. To prevent its use for human consumption, it is made unfit for drinking by adding a poisonous substance like copper sulphate.

(b) CH3CH2OH → CH2 = CH2 + H2O

(c) Concentrated sulphuric acid acts as a catalyst in the esterification reaction.

Explain why carbon forms compounds mainly by covalent bond. Explain in brief two main reasons for carbon forming a large number of compounds. Why does carbon form strong bonds with most other elements? [CBSE 2015]

Carbon has no tendency to lose electrons easily. Similarly, it has no tendency to gain electrons. It completes its octet buy sharing the electrons other atoms. Therefore, carbon forms compounds mainly by covalent bonds.
Two main resources for carbon forming a large number of compounds are given below:
Catenation: It is the property of carbon to link with other carbon atoms to form straight chain, branched chain or cyclic compounds. Thus, carbon forms a large number of compounds containing 2, 3, 4, 5…. etc., carbon atoms.
Tetravalency; Carbon has four electrons in the outermost shell. It shares these four electrons with four electrons from four other monovalent atoms. Carbon has the tendency to form bonds with hydrogen, oxygen, nitrogen and halogens. This increases the number of compounds of carbon.
Carbon forms strong bonds with most other elements: This is because carbon has a small atomic size. It can hold strongly the four pairs of electrons. That it shares with other atoms. Therefore, it forms strong bonds with other elements.

(a) Give a chemical test to distinguish between saturated and unsaturated hydrocarbon. (b) Name the products formed when ethane burns air. Write the balanced chemical equation for the reaction showing the types of energies liberated. (c) Why is reaction between methane and chlorine in the presence of sunlight considered a substitution reaction? [CBSE 2016]

(a) Saturated hydrocarbons give a clean flame on burning while unsaturated carbon compounds will give a yellow flame with a lot of black smoke.

(b) Ethane burns in air to form carbon dioxide and water.
2C2H6 + 702 → 4CO2 +6H2O +Heat +Light

(c) Reaction between methane and chlorine in the presence of sunlight is a substitution reaction because hydrogen atoms in methane are successively replaced or substituted by chlorine atoms.

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10th Science Chapter 4 Board Questions Set – 10 (5 Marks)
A compound A(C2H4O2) reacts with Na metal to form a compound B and evolves a gas which burns with a pop sound. Compound A on treatment with an alcohol C in the presence of an acid forms a sweet smelling compound, D(C4H8O2). On addition of NaOH to D gives back B and C. Identify the A, B, C, D. Write the reactions involved. [CBSE 2018]

The compounds A, B, C, D are given as under:
A = CH3COOH
B = CH3COONa
C = C2H5OH
D = CH3COOC2H5

The reactions are explained as under:
2CH3COOH + 2Na → 2CH3COONa + H2
CH3COOH + C2H5OH → CH3COOC2H5 + H2O
CH3COOC2H5 + H2O → CH3COOH + C2H5OH

Explain why it is difficult to wash clothes with soap when water is hard? How do detergent help in overcoming the problem? [CBSE 2012]

The structure of synthetic detergent is similar to that of soaps. They have a long hydrocarbon chain which is water repelling and a short ionic part which is water attracting. The water attracting group in a synthetic detergent usually a sodium sulphonate group (SO3-Na+) or sodium sulphate group(SO4-Na+) The cleaning action of soap and detergent are similar. Thus chemically these they are not different. Difference lies only in the hydrocarbon part. Synthetic detergent made from long chain hydrocarbon obtained from petroleum whereas hydrocarbon part of soap or vegetable oils. In soaps water attracting part is –COONa whereas in detergent it is –SO3Na. Detergent is being preferred to soap because these form lather even with hard water and have better cleaning action.

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