CBSE Class 10 Chemistry Carbon And Its Compounds Worksheet Set F

Question. A carbon compound contains two atoms of carbon. Which name should the carbon compound bear?
(a) Butane
(b) Ethane
(c) Methane
(d) Propane

Answer: B

Question. While cooking ,if bottom of the vessel is getting blackened on the outside, it means that
(a) The food is not cooked properly
(b) The fuel is not burning properly
(c) The fuel is wet
(d) The fuel is burning completely

Answer: B

Question. The hetero atoms present in CH₃-CH₂-O-CH₂-CH₂-Cl are
(i)oxygen (ii) carbon
(iii ) hydrogen (iv) chlorine
(a) (i) and (ii)
(b) (ii) and (iii)
(c)(iii) and (iv)
(d) (i) and (iv)

Answer: D

Question. Carbon forms four covalent bonds by sharing its four valance electrons with four univalent atoms, e.g hydrogen. After the formation of four bonds, carbon attains the electronic configuration of
(a) helium
(b) neon
(c) argon
(d) krypton

Answer: B

Question. When ethanoic acid reacts with ethanol a sweet smelling product is formed . The functional group present in the product is
(a) Aldehyde
(b) Ketone
(c) Alcohol
(d) Ester

Answer: D

Question. The image represents a chemical reaction where ethanol is oxidized using potassium dichromate and sulphuric acid.
Which option represents the product “X”?
(a) CH₂O
(b) CH₃OH
(c) CH₃H₂O
(d) CH₃COOH

Answer: D

Question. The number of structural isomers for alkane with a molecular weight 72 is
(a) 2
(b) 3
(c) 4
(d) 5

Answer: B

Question. The image represents the structure of a carbon compound known as ethane.
Which option explains the naming of ethane?
(a) the presence of functional group connected with a single bond
(b) as it contains two carbon atoms and a single bond connects the carbon atoms
(c) carbon compound with a total number of eight atoms are named as ethane
(d) as it contains six hydrogen atoms and a single bond connects the carbon and hydrogen atom

Answer: B

Question. The property of carbon atom by virtue of which it forms bond with other carbon atom is called
(a) chemical bonding
(b) polymerization
(c) catenation
(d) carbonization

Answer: C

Question. The image represents a carbon compound.
Which functional group is present in the compound?
(a) alcohol
(b) aldehyde
(c) carboxylic acid
(d) ketone

Answer: D

ASSERTION AND REASON QUESTIONS:

DIRECTION: Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Question. Assertion(A) : Diamond and graphite are allotropes of carbon.
Reason (R) : Some elements can have several different structural forms while in the same physical state. These forms are called allotropes.

Answer: A

Question. Assertion (A) : Carbon monoxide is extremely poisonous in nature.
Reason (R) : Carbon monoxide is formed by complete combustion of carbon.

Answer: C

Question. Assertion(A) : Carbon compounds can form chain, branched and ring structures.
Reason (R) : Carbon exhibits the property of catenation.

Answer: A

Question. Assertion(A) : Carbon is the only element that can form large number of compounds.
Reason (R) : Carbon is tetravalent and shows the property of catenation.

Answer: D

Question. Assertion(A) : Soaps are not suitable for washing purpose when water is hard.
Reason (R) : Soaps have relatively weak cleansing action.

Answer: B

Question. Assertion(A) : If the first member of a homologous series is methanal, its third member will be propanal.
Reason (R) : All the members of a homologous series show similar chemical properties.

Answer: B

CASE STUDY BASED QUESTIONS:

1. Read the following and answer the questions :
The compounds which have the same molecular formula but differ from each other in physical or chemical properties are called isomers and the phenomenon is called isomerism. When the isomerism is due to difference in the arrangement of atoms within the molecule, without any reference to space, the phenomenon is called structural isomerism. In other words. structural isomers are compounds that have the same molecular formula but different structural formulas, i.e., they are different in the order in which different atoms are linked. In these compounds, carbon atoms can be linked together in the form of straight chains, branched chains or even rings.

Question. Which of the following is an isomeric pair?
(a) Ethane and propane
(b) Ethane and ethene
(c) Propane and butane
(d) Butane and 2-methylpropane

Answer: A

Question. The number of isomers of pentane is
(a) 2
(b) 3
(c) 4
(d) 5

Answer: B

Question. Which of the following sets of compounds have same molecular formula?
(a) Butane and iso-butane
(b) Cyclohexane and hexene
(C) Propanal and propanone
(d) All of these

Answer: D

Question. Among the following the one having longest chain is
(a) neo-pentane
(b) iso-pentane
(C) 2-methylpentane
(d) 2,2-dimethylbutane

Answer: C

Question. In order to form branching, an organic compound must have a minimum of carbon atoms
(a) 2
(b) 3
(c) 4
(d) 5

Answer: C

2. Read the following and answer the questions :
Food, clothes, medicines, books, or many of the things are all based on this versatile element carbon. In addition, all living structures are carbon based. The earth’s crust has only 0.02% carbon in the form of minerals. The element carbon occurs in different forms in nature with widely varying physical properties. Both diamond and graphite are formed by carbon atoms, the difference lies in the manner in which the carbon atoms are bonded to one another. Carbon has the unique ability to form bonds with other atoms of carbon, giving rise to large molecules. This property is called catenation.

Question. Which of the following are isomers?
(a) Butane and isobutene
(b) Ethane and ethene
(c) Propane and propyne
(d) Butane and isobutane

Answer: D

Question. Which one of the following is not an allotrope of carbon?
(a) Soot
(b) Graphite
(c) Diamond
(d) Carborundum

Answer: D

Question. From the given alternatives, whose chemical and physical properties are not same?
(a) Graphite and Diamond
(b) Phosphorous and Sulphur
(c) Carbon and Hydrogen
(d) Methyl alcohol and Acetic acid

Answer: D

Question. Pentane has the molecular formula C₅H₁₂. It has
(a) 5 covalent bonds
(b) 12 covalent bonds
(c) 16 covalent bonds
(d) 17 covalent bonds

Answer: C

Question. Which of the following statements is not correct?
(a) Graphite is much less dense than diamond
(b) Graphite is black and soft
(c) Graphite has low melting point
(d) Graphite feels smooth and slippery

Answer: C

Question. Write an activity to show the acidic nature of ethanol. Give the chemical equation of the reaction taking place.
Answer: Take ethanol in a test tube and drop a small piece of sodium about the size of a grain of rice into it. The reaction evolves a colourless gas which is hydrogen.
Hydrogen gas can be tested by bringing a burning splinter/match stick near the mouth of the test tube, it burns with the popping sound.
This activity proves that ethanol like other acids release H₂ gas
2Na + 2CH₃CH₂OH ⎯⎯→ 2CH₃CH₂ONa + H2

Question. A, B, C are members of homologous series their melting points are –183°C, –138°C, 130°C respectively. Among these
(i) Which member will have least number of carbon atoms?
(ii) Which member will have maximum number of carbon atoms?
Answer: (i) A will have least number of carbon atoms.
(ii) C will have maximum number of carbon atoms.

Question. Take about 20 ml of castor oil in a beaker. Add 30 ml of 20% sodium hydroxide solution. Heat the mixture with continuous stirring for a few minutes till the mixture thickens. Add 5–10 g of common salt to this. Stir the mixture well, allow it to cool, soaps is obtained.
(a) Why do we use common salt to make soap?
(b) What will happen if you will add the above made soap solutions to the following test tubes A, B, and C.
(c) Can we use potassium hydroxide instead of sodium hydroxide.

Answer: (a) Salt: NaCl is added while making soap, because it will help the reaction to occur faster and adds sodium ion to increase the reaction rate.
(b) In test tube A: Soap + Oil ⎯→ Lather/foam is formed. Carboxylic chain dissolves in oil.
In test tube B: Soap + Hard water ⎯→ Insoluble compound called scum is formed.
In test tube C: Soap + soft water ⎯→ Froth is formed.
(c) Yes, we can use potassium hydroxide to prepare soap.

Question. A compound ‘X’ has molecular formula C₂H₆O is saturated hydrocarbons and is a very good solvent. How can you convert it into unsaturated hydrocarbon? Identify X and show its conversion with the help of equation.
Answer: X’ is CH₃—CH₂OH ethanol. It can be made unsaturated by heating it with conc.
H₂SO₄ which is a dehydrating agent removes water from it, thereby forming ethene.

Question. A hydrocarbon compound A is active ingredient of wine and cough syrup. A on oxidation with acidified K₂Cr₂O₇ forms compound B. Identify the compound A and B and write the chemical equations involved.
Answer: A is ethanol, C₂H₅OH
B is ethanoic acid, CH₃COOH

Long Answer Type Questions

Question. An organic compound ‘A’ is widely used as a preservative in pickles and has a molecular formula C2H4O2. This compound reacts with ethanol to form a sweet smelling compound ‘B’.
(a) Identify the compound ‘A’.
(b) Write the chemical equation for its reaction with ethanol to form compound ‘B’.
(c) How can we get compound ‘A’ and ‘B’?
(d) Which gas is obtained when compound ‘A’ reacts with washing soda? Give the equation.
(e) Write an equation to obtain ‘A’ back from ‘B’.
Answer: (a) ‘A’ is CH₃COOH acetic acid.
(b) CH₃COOH + C₂H5OH → CH₃COOC₂H₅ + H₂O
(c) We can get compound A back by the process of saponification.
(d) A + washing soda → CO₂ gas is produced
2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂
(e) Saponification

Question. (a) What do you mean by allotropy?
(b) What is isomerism?
(c) Give one example of homologus series, give two properties of it.
(d) What is the full form of IUPAC?
Answer: (a) Allotropy: It is the property of an element in which element show same chemical properties but different physical properties, due to difference in the bonding of atoms.
Example: Diamond and graphite are having same chemical properties but they look/appear to be physically different as the bonding in both differs.

(b) Isomerism: It is the property of hydrocarbons which show same molecular formula but exhibits different structural formulae.
Example: Butane

Both of them show different properties.
(c) Homologous series: When the members of a hydrocarbon family obey same general formula they are said to be in homologous series. When the members are arranged in increasing order of their molecular masses:
Example: Alkane – CnH_2n+2
CH₄ — Methane
C₂H₆ — Ethane
C₃H₈ — Propane
C₄H₁₀ — Butane
Properties:
(i) The difference between two consecutive members of homologous series is of —CH2 and mass 14 a.m.u.
(ii) They all show same chemical properties and slight gradation in their physical properties.
(d) IUPAC: International Union of Pure and Applied Chemistry.

Question. (a) What is a functional group in a carbon compound? Identify the functional group present in CH3COOH and C2H5OH.
(b) State the principle on which the cleansing action of soap is based.
Answer: (a) The atom or group of atoms which determines the properties of a compound is called functional group.
— OH is alcohol group
— COOH is carboxylic group 
(b) Cleansing action of soap depends on its structure, it has two ends hydrophobic which attracts dirt, oil or grease and hydrophilic end which attracts water.

The dirt is carried by hydrophobic portion which is attached to hydrophilic end which gets attached to water and is washed away.

Question. (a) What are hydrocarbons?
(b) Give difference between saturated and unsaturated hydrocarbons.
(c) Why does carbon form large number of compounds?
Answer: (a) Hydrocarbons – A compound of carbon and hydrogen.
(b)

(c) Carbon forms large number of compounds due to
(i) Catenation – Self linking property which leads to long straight chains, branched chains and cyclic chains.
(ii) Isomerism – Compound of carbon can exist in more than one structural formula but has same molecular formula.
(iii) Tetravalency – To acquire noble gas configuration, carbon shares its outer electrons with other elements, thus form covalent bond with other elements.

Question. (a) Why does carbon form compounds mainly by covalent bonding?
(b) List any two reasons for carbon forming a very large number of compounds.
(c) An organic acid ‘X’ is a liquid which often freezes during winter time in cold countries, has the molecular formula, C2H4O2. On warming it with ethanol in the presence of a few drops of concentrated sulphuric acid, a compound ‘Y’ with a sweet smell is formed.
(i) Identify ‘X’ and ‘Y’.
(ii) Write a chemical equation for the reaction involved.
Answer: (a) Carbon forms compounds mainly by covalent bonding because carbon has small size, so neither it can loose four electrons easily, because very high amount of energy will be required, nor it can gain four electrons. Hence, it shares four electrons forming covalent bonds.
(b) (i) Due to catenation – Self linking property
(ii) Tetravalency of carbon – Forms compounds with other elements.
(c) (i) ‘X’ is CH₃COOH, it freezes during winter in cold countries.
‘Y’ is ester CH₃COOC₂H₅

Question. (i) Explain the formation of calcium chloride with the help of electron dot structure. (At numbers: Ca = 20; Cl = 17)
(ii) Why do ionic compounds not conduct electricity in solid state but conduct electricity in molten and aqueous state?.
Answer:

(ii) Ionic compounds do not conduct in solid state due to absence of free ions but they conduct electricity in molten and aqueous state due to presence of free ions.

Question. What are soaps? Explain the mechanism of the cleansing action of soaps? Soaps form scum
with hard water. Explain why? How this problem is overcome by use of detergents?
Answer: Soaps are sodium salts of fatty acids. It is biodegradable and shows cleansing action by removing dirt.
Mechanism of cleansing action: Soap has molecules with tadpole like structure.

Its head is made of Na⁺ ion which is hydrophilic and long tail is made up of hydrocarbon chain which is hydrophobic, it attracts the dirt and removes it. When soap is added to water it forms micelles and helps in removing the dirt which sticks to the carbon chain. On rinsing the cloth with water it helps in removing the dirt, as Na+ is hydrophilic. It attracts water and carries its tail entangled with dirt and flows away with water.
Scum formation: Soaps form scum with hard water because hard water has salts of calcium and magnesium which react with soap to form insoluble compound called scum.
In case of detergents, the salts present in hard water does not react with the molecules of detergent to form insoluble compound called scum, but the molecules of detergent remain as it is and helps in the cleansing action.

Question. Atoms of an element contain five electrons in its valence shell. This element is the major component of air. It exists as a diatomic molecule.
(i) Identify the element.
(ii) Show the bond formed between two atoms of this element.
(iii) Write the nature of bond between the two atoms.
Answer:

Question. (a) What is homologous series of compounds? List any two characteristics of a homologous series.
(b) (i) What would be observed on adding 5% solution of alkaline potassium permanganate solution drop by drop to some warm ethanol taken in a test tube?
(ii) Write the name of the compound formed during the chemical reaction.
(c) How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property? (CBSE 2008)
Answer: (a) Organic compounds when arranged in series having same general formula and similar chemical properties is called homologous series.
Two characteristics of homologous series.
(i) Each successive member differ by —CH₂ group, 14 u.
(ii) The method of preparation and chemical properties of members of homologous series is same.
(b) (i) The colour of KMnO₄ will get discharged because ethanol gets oxidised to form ethanoic acid.

(ii) Ethanoic acid
(c) On adding sodium bicarbonate solution to both the test tubes containing ethanol and ethanoic acid then the test tube containing carboxylic acid (ethanoic acid) will show brisk effervescence due to formation of CO2 gas. Alcohol will not react with sodium bicarbonate 

Question. Carbon, group 14 element in the periodic table, is known to form compounds with many elements.
Write an example of a compound formed with (i) Chlorine, (ii) Oxygen.
Answer:

Question. In electron dot structure, the valence shell electrons are represented by crosses or dots.
(i) The atomic number of chlorine is 17. Write its electronic configuration.
(ii) Draw the electron dot structure of chlorine molecule.
Answer: