CBSE Class 10 Science Carbon and its compounds Assignment Set A

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Carbon And Its Compounds Class 10 Science Assignment Pdf

Class 10 Science students should refer to the following printable assignment in Pdf for Carbon And Its Compounds in standard 10. This test paper with questions and answers for Grade 10 Science will be very useful for exams and help you to score good marks

Class 10 Science Assignment for Carbon And Its Compounds


Question : What are isomers? Draw the structure of two isomers of butane C4H10.
Answer :  The organic compounds having the same molecular formula but different structures are known as isomers. Isomers of butane C4H10.

Carbon and its compounds Assignment_1


Question : Name the functional group present in each of the following organic compounds.
(i) C2H5Cl (ii) C2H5OH
Answer : Functional group present in:
(i) C2H5Cl – chloro(halide) (ii) C2H5OH —- Alcohol


Question : Write the electron dot structure of ethane molecule, C2H4
Answer :

Carbon and its compounds Assignment_2


Question : Write the name and structure of an alcohol with three carbon atoms in its molecule.
Answer : Name of an alcohol: Propanol
Structure of propanol: H2C – CH2 – CH– OH

Carbon and its compounds Assignment_3


Question : Write the name and formula of the 2nd member of homologous series having general
Formula CnH2n.

Answer : CnH2n: alkene Name: propene(2nd member) formula: C3H6


Question : What are covalent compounds? Why are they different from ionic compound? List any Three characteristics properties.
Answer :  (i) The chemical bond formed by the sharing of electrons between two atoms is known as a covalent bond. The molecules formed by sharing of electrons between two or more same atoms or between two or more non-metals are called covalent compound.
(ii)Covalent compounds are different from ionic compounds as ionic compounds are Formed by transfer of electrons.
Characteristics of covalent compound:
(i) Covalent compounds usually have low melting and boiling point because force Of attraction between molecules is very weak.
(ii) Covalent compounds are usually insoluble in water but they are soluble in organic compound.
(iii) Covalent compounds do not conduct electricity as they do not contain ions.



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

Answer : B
Question : Hardness of water is caused by: 
a. All of these
b. Mg(HCO3)2
c. CaCl2
d. CaSO4

Answer : A 
Question : Which of the following are not straight chain compounds? 
a. A, B and D
b. C and D
c. A and B
d. A and C

Answer : B
Question : What is denatured spirit? 
a. None of these
b. Ethanol only
c. Methanol only
d. Ethanol + Methanol (5%)

Answer : D
Question : Alcohols can be produced by the hydration of: 
a. Alkenes
b. Alkanes
c. Acids
d. Alkynes

Answer : A 

Very Answer Type Questions :

Question : Name the chemical reagent which oxidises ethanol to ethanoic acid. 
Answer : Ethanol is oxidised by acidifed sodium dichromate in a test-tube reaction, firstly to form ethanal and, with further oxidation, ethanoic acid.
Question : Why is pure ethanoic acid called glacial ethanoic acid (or glacial acetic acid)? 
Answer :  The melting point of pure ethanoic acid is 290 K. When ethanoic acid (acetic acid) is cooled below 10 °C, it freezes to form a colourless, ice-like solid. The solid looks like glacier and hence pure ethanoic acid is called glacial ethanoic acid (or glacial acetic acid). 
Question : State the part of soap molecule that attaches itself to dirt when soap is dissolved in water. 
Answer : Hydrophobic end also called as tail, i.e.long hydrocarbon chain moves away from water but attaches to dirt.

Question : Write the molecular formula of first two members of homologous series having functional group -Br. 
Answer : CH3Br, C2H5Br 

Question : Write the name and structure of an aldehyde with four carbon atoms in its molecule.
Answer : 
CBSE Class 10 Science Carbon and its compounds Assignment Set A_1

Question : How are covalent bonds formed ?
Answer : Covalent bonds are formed by the sharing of electrons between the atoms. 

Question : Write the molecular formula of the 2nd member of the homologous series where the first member is ethyne. 
Answer : C3H4, C4H6 

Question : Which element exhibits the property of catenation to maximum extent and why ?
Answer : Carbon, due to strong C—C bond. 

Question : Write the molecular formula of first two members of homologous series having function group – Cl.
Ans. The molecular formula of first two consecutive members of this series is:
CH3Cl (Chloromethane)
C2H5Cl (Chloroethane) 

Question : Name a cyclic unsaturated carbon compound.
Answer : Benzene. 

Question : Write the name and structure of an alcohol with three carbon atoms in its molecule.
Answer : Propanol,
CBSE Class 10 Science Carbon and its compounds Assignment Set A_2

Question : What is a homologous series of carbon compounds ?
Answer : A homologous series is the family of organic compound having the same functional group, and the successive (adjacent) members of which differ by CH2 unit or 14 atomic mass unit. 

Question : Write the molecular formula of the 2nd and the 3rd member of the homologous series whose first member is methane. 
Answer :. Ethane (C2H6)
Propane (C3H8

Question : Define catenation. 
Answer : The property of self-linking of atoms of an element through covalent bonds in order to form straight chain, branched chains or cyclic chains of different sizes is called catenation. 

Question : Write the next homologue of each of the following:
(i) C2H4
(ii) C4H6

Answer : (i) C3H6
(ii) C5H8 

Question : Write the name and formula of the 2nd member of homologous series having general formula CnH2n.
Answer : Name: Propene
Formula: C3H6

Question : Name the following compounds:
(i) CH3—CH2—OH, 
Answer : (i) Ethanol 

Question : Write the name and structure of an aldehyde with four carbon atoms in its molecule.
Answer : 
CBSE Class 10 Science Carbon and its compounds Assignment Set A_3

Question : Name the functional group present in propanone.
Answer : Ketone. 

Question : Write the number of covalent bonds in the molecule of ethane.
Answer : Seven covalent bonds. 

Question : Select saturated hydrocarbons from the followings:
C3H6 , C5H10 , C4H10 , C6H14 , C2H4
Answer : C4H10; C6H14

Question : Write the molecular formula of the 2nd and 3rd member of the homologous series whose first member is ethene. 
Answer : C3H6 and C4 H

Question : Name the process of converting vegetable oil to vegetable ghee. 
Answer : Hydrogenation. 

Question : State the general formula of carboxylic acids. 
Answer :  The general formula of carboxylic acids is CnH2n+1COOH.

Short Answer Type Questions :

Question : Explain why soaps are not effective cleansing agents in hard water? 
Answer : It is because detergents form lot of lather even with hard water. Hard water contains Ca2+ and Mg2+ ions which react with soap to form Insoluble salts of calcium and magnesium called scum and soap goes waste. Detergents do not form insoluble compounds with Ca2+ and Mg2+ ions therefore. These are more effective.
Question : Write the molecular formula and structural formula of acetaldehyde. 
Answer :   Molecular formula of acetaldehyde : CH3CHO
Structural formula of acetaldehyde:
Question : Explain the formation of scum when hard water is treated with soap. 
Answer : Soap does not work properly when the water is hard. A soap is a sodium or potassium salt of long chain fatty acids. Hard water contains salts of calcium and magnesium.
When soap is added to hard water, calcium and magnesium ions present in water displace sodium or potassium ions from the soap molecules forming an insoluble substance called scum. A lot of soap is wasted in the process.

Question : Give reason why carbon can neither form C4+ cations nor C4– anions, but forms covalent compounds. Also, state the reason to explain why covalent compounds are bad conductors of electricity and have low melting and boiling points? 
Answer : Carbon cannot form C4+ cation because removal of 4 electrons from a carbon atom would require a large amount of energy. 
Carbon cannot form C4– anion because it would be difficult for the nucleus with 6 protons to hold on to 10 electrons.
Hence, carbon atoms share electrons forming covalent compounds. 
Covalent compounds do not form ions/ charged particles and therefore do not conduct electricity. 
Inter-molecular forces of attraction are weak, hence they have low melting and boiling points. 

Question : An aldehyde as well as a ketone can be represented by the same molecular formula, say C3H6O. Write their structures and name them. State the scientific relation between the two.
Answer : (i) Propanal (aldehyde); 
CBSE Class 10 Science Carbon and its compounds Assignment Set A_4
(iii) Isomers (same molecular formula but different structural formula/different functional group)

Question : Give a test that can be used to confirm the presence of carbon in a compound. With a valency of 4, how is carbon able to attain noble gas configuration in its compounds? 
Answer : When carbon compound is burnt in the presence of oxygen, a gas is evolved. Gas evolved turns lime water milky.
By sharing its four valence electrons with other elements, carbon attains stable noble gas configuration. 

Question : What are covalent compounds? How are they different from ionic compounds? List any two properties of covalent compounds.
Answer : The compounds that are formed due to sharing of electrons between two atoms/compounds having covalent bonds. 
Ionic compounds are formed due to transfer of electrons from one atom to another/compounds having ionic bonds/compounds having attraction between oppositely charged ions 
(i) They are poor conductors of electricity 
(ii) They have low melting and boiling point. 

Question : What is meant by isomers ? Draw the structure of two isomers of butane, C4H10. Explain why we cannot have isomers of first three members of alkane series.
Answer : Isomers are the compounds which have the same molecular formula but different structural formula.
Isomers of Butane:
CBSE Class 10 Science Carbon and its compounds Assignment Set A_5
We cannot have isomers of the first three members of the alkane series because of the following laws of isomers:
(i) The parent chain should have the most number of carbon atoms.
(ii) The branching cannot be done from the first and the last carbon atom of the structure. 

Question : The number of carbon compounds is more than those formed by all other elements put together. Justify the statement by giving two reasons.
Answer : (i) Due to self linking ability of carbon/catenation.
(ii) Since carbon has a valency of four it can form bonds with four other atoms of carbon or atoms of some other monovalent element.
(iii) Due to small size of carbon it forms very strong and (or) stable bonds with other elements.

Question : (a) Why most of the carbon compounds are poor conductor of electricity ?
Answer : (a) Carbon compounds form covalent bonds/do not dissociate into ions/do not have charged particles (ions)/do not have free electrons.

Question : Draw the structures of the following compounds and identify the functional group present in them:
(i) Butanoic acid
(ii) Bromopropane
(iii) Butyne 
Answer : 
CBSE Class 10 Science Carbon and its compounds Assignment Set A_6

Question : What is a homologous series of carbon compounds?
Give an example and list its three characteristics.
Answer : A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series. 
Example: Alkane / Alkene / Alkyne / Alcohol or any other one correct example.
(i) They have same general formula.
(ii) They have same functional group.
(iii) The difference in the molecular mass of two successive member is 14u.
(iv) The difference in the molecular formula of two successive member is of CH2 unit.
(v) They have similar chemical properties.

Question : Which compounds are called (i) alkanes, (ii) alkenes and (iii) alkynes ? C4H10 belongs to which of these? Draw two structural isomers of this compound.
Answer : • Alkane
Saturated hydrocarbon with C–C single bond
• Alkene
Unsaturated Hydrocarbon with double bond in C=C
• Alkyne
Unsaturated Hydrocarbon with triple bond in C ≡ C
• Alkane 
2 structural isomers
CBSE Class 10 Science Carbon and its compounds Assignment Set A_7

Question : How would you distinguish experimentally between an alcohol and a carboxylic acid? 
Answer :  The following two tests are used:
i. Litmus test: Treat the given compound with blue litmus solutions. If the blue litmus solution turns red, it is a carboxylic acid and if does not turn red, it is an alcohol.

ii. Sodium bicarbonate test: Add some sodium bicarbonate solution to the given compound. If there is a brick evolution of a colourless and odourless gas (CO2 ) which turns freshly prepared lime water milk, it is carboxylic acid and if there is no effervescence, it is an alcohol.  
Long Answer Type Questions :
Question : i. What are hydrocarbons? Give examples.
ii. Give the structural differences between saturated and unsaturated hydrocarbons with two examples each.
iii. What is functional group? Give examples of four different functional groups. 
Answer : i. The compounds that are made up of carbon and hydrogen atoms are called hydrocarbons, e.g. methane (CH4), ethane (CH2 = CH2). Ethyne (C2H2), cyclohexane (C6H12), benzene (C6H6)etc.
ii. In saturated hydrocarbons, all the four valencies of carbon are satisfied by a single covalent bond while in unsaturated hydrocarbons, double or triple bonds are required to satisfy the valencies of carbon, e.g.
a. Saturated hydrocarbons
Methane (CH4), Ethane (CH3 — CH3)
b. Unsaturated hydrocarbons
Ethene (H2C = CH2), Ethyne (HC ≡ CH)
iii. A functional group is an atom or group of atoms that define the structure (or the properties) of organic compounds. The four examples are:
a. -OH Alcohol
b. -COOH Carboxylic acid
c. -CHO Aldehyde
d. -X Halogen 

Question : Why are certain compounds called hydrocarbons ? Write the general formula for homologous series of alkanes, alkenes and alkynes and also draw the structure of the first member of each series. Write the name of the reaction that converts alkenes into alkanes and also write a chemical equation to show the necessary conditions for the reaction to occur. 
Answer : The hydrocarbons are the compounds that consist of carbon and hydrogen.
The alkanes are known as the saturated hydrocarbons as they have compounds of carbon that are single bonded and has the general formula CnH2n+2
Alkenes are unsaturated hydrocarbons and are made up of compounds of carbon that are double bonded and has the general formula CnH2n.
Alkynes are also unsaturated hydrocarbons that are made up of compounds of carbon that are triple bonded and have a general formula CnH2n – 2
The structure of the first members of each series are as follows:
CBSE Class 10 Science Carbon and its compounds Assignment Set A_8
The hydrogenation reaction is a reaction that helps in converting unsaturated hydrocarbons to the saturated hydrocarbons. The conversion of alkenes to alkane is an example of hydrogenation reaction.
CBSE Class 10 Science Carbon and its compounds Assignment Set A_9

Question : What is methane ? Draw its electron dot structure. Name the type of bonds formed in this compound. Why are such compounds: (i) poor conductors of electricity and (ii) have low melting and boiling points ? What happens when this compound burns in oxygen ?
Answer : Methane is a colourless and highly flammable gas produced on decomposition of vegetation naturally in marshlands. It is the simplest hydrocarbon (CH4).
Electron dot structure:
All the bonds present between four hydrogen atoms and one carbon atom at the centre are covalent bonds.
(i) Methane is a poor conductor of electricity as all the bonds present are covalent bonds. Hence, no free electrons are available for conduction of electricity.
(ii) As force of attraction between the molecules are not very strong in covalently bonded carbon compounds, therefore, methane being a covalent compound has very low melting and boiling point.
When methane burns in oxygen, carbon dioxide, water and large amount of heat and light is released.
CH4 + 2O2 → CO2 + 2H2O + heat and light

Question : i. Write the names of the functional groups in
ii. Describe a chemical test to distinguish between ethanol and ethanoic acid.
iii. Write a chemical equation to represent what happens when hydrogen gas is passed through an unsaturated hydrocarbons in the presence of nickel as a catalyst? 
Answer :
i. a. Ketone (R-CO-R)

b. Aldehyde (R-CHO)

ii. Distinguish between ethanol and ethanoic acid:

a. Ethanol does not react with metal carbonate while ethanoic acid reacts with metal carbonates to form salt, water and CO2.

e.g. 2CH3COOH + Na2CO→ 2CHCOONa + CO2+ H2

b. Ethanol does not react with NaOH while ethanoic acid reacts with NaOH to form sodium ethanoate and water


c. Ethanol can undrergo oxidation to produce aldehyde and futher it can oxidize to produce acid.

iii. saturated hydrocarbon is obtained as hydrogen gas passed through unsaturated hydrocarbon. The reaction is an example of addition reaction better known by the name of hydrogenation reaction.
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