CBSE Class 10 Science Carbon and its compounds Assignment Set E

Read and download free pdf of CBSE Class 10 Science Carbon and its compounds Assignment Set E. Get printable school Assignments for Class 10 Chemistry. Class 10 students should practise questions and answers given here for Chapter 4 Carbon And Its Compound Chemistry in Class 10 which will help them to strengthen their understanding of all important topics. Students should also download free pdf of Printable Worksheets for Class 10 Chemistry prepared as per the latest books and syllabus issued by NCERT, CBSE, KVS and do problems daily to score better marks in tests and examinations

Assignment for Class 10 Chemistry Chapter 4 Carbon And Its Compound

Class 10 Chemistry students should refer to the following printable assignment in Pdf for Chapter 4 Carbon And Its Compound in Class 10. This test paper with questions and answers for Class 10 Chemistry will be very useful for exams and help you to score good marks

Chapter 4 Carbon And Its Compound Class 10 Chemistry Assignment

Important MCQs for NCERT Class 10 Science Carbon and its Compounds

Question : Which of the following structures correctly represents the electron dot structure of a chlorine molecule:

CBSE Class 10 Science Chemistry Carbon and its compounds Assignment

Answer : A

Question : While cooking, if the bottom of the vessel 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 wet
D) The fuel is burning completely

Answer :  B


Question : Cation is formed when:
A) Atom gains electrons
B) Atom loses electrons
C) Proton is lost by the atom
D) Atom shares electrons

Answer :  B


Question : The property of self-linkage among identical atoms to form long chain compounds is known as:
A) Catenation
B) Isomerisation
C) Superposition
D) Halogenation

Answer :  A


Question : Which of the following statements about graphite and diamond is true:
A) They have the same crystal structure
B) They have the same degree of hardness
C) They have the same electrical conductivity
D) They can undergo the same chemical reactions

Answer :  D


Question : The byproduct of soap is:
A) Isoprene
B) Glycerol
C) Butane
D) ethylene glycol

Answer :  B


Question : Carbon exists in the atmosphere in the form of:
A) Only carbon monoxide
B) Carbon monoxide in traces and carbon dioxide
C) Only carbon dioxide
D) Coal

Answer :  C


Question : A molecule of ammonia (NH3) has:
A) Only single bonds
B) Only double bonds
C) Only triple bonds
D) Two double bonds and one single bond

Answer :  A


Question : In which of the following compounds -OH is the functional group:
A) Butanone
B) Butanol
C) Butanoic
D) Butanal

Answer :  B


Question : Chlorine reacts with saturated hydrocarbons at room temperature in the:
A) absence of sunlight
B) presence of sunlight
C) presence of water
D) presence of hydrochloric acid

Answer :  B


Question : Hydrocarbon are compounds made of:
A) C & H
B) C & O
C) C & H2O
D) C & He

Answer :  A


Question : Which among the following can react with sodium metal:
A) Ethane
B) Propane
C) Ethanol
D) Ethene

Answer :  C


Question : –CHO Group is:
A) Aldehydic group
B) Alcholic group
C) Ketonic group
D) Acidic Group

Answer :  A


Question : Natural Rubber is a polymer of:
A) Chloroprene
B) Isoprene
C) Propene
D) Neoprene

Answer : B


Question : The number of covalent bonds in C4H10 is:
A) 10
B) 11
C) 12
D) 13

Answer : D

 

Question : Match the following with the correct response: 
Ma-14
a. 1-D, 2-A, 3-C, 4-B
b. 1-B, 2-D, 3-A, 4-C
c. 1-C, 2-B, 3-D, 4-A
d. 1-A, 2-C, 3-B, 4-D
 
Answer : D
Explanation: Ionic bonds are formed between cations and anions. Catenation is the linkage of atoms of the same element into longer chains. Catenation occurs most readily in carbon. Pyridine is added to alcohol to make it unsuitable for drinking. Most of the synthetic detergents are nonbiodegradable. They cannot be decomposed by micro-organisms like the bacteria. 
 
Question : Hydrocarbon with molecular formula has: 
a. 10 covalent bonds
b. 7 covalent bonds
c. 13 covalent bonds
d. 6 covalent bonds
 
Answer : C
Explanation: Butane C4H10 has 3 C-C covalent bonds and 10 C-H covalent bonds. Thus, it has 13 covalent bonds. 
 
Question : The structural formula of an ester from which an acid and an alcohol is formed is as follows. Name the acid and the alcohol. 
A-8
a. Formic acid, Ethanol
b. Ethanoic acid, Ethanol
c. Propanoic acid, Methanol
d. Formic acid, Propanol
 
Answer : D
Explanation: HCOOCH2CH2CH3 + H2O --> HCOOH + CH3 CH2CH2OH
The ester is HCOOCH2CH2CH3. The product HCOOH is formic acid or methanoic acid (carboxylic acid) and CH3CH2CH2OH is propanol (alcohol).
 
Question : The functional group present in ethanol is: 
a. Carboxyl group
b. Ester group
c. Alcoholic group
d. Aldehydic group
 
Answer : C
Explanation: The functional group present in ethanol (C2H5OH) is the alcoholic group (-OH group). The hydroxyl group attached to a carbon atom is known as alcohol group. 


Assertion and Reasoning Based Questions

Directions : In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as :
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false but reason is true.

Question. Assertion : Carbon and its compounds are used as fuels.
Reason : They give lot of heat and light when burnt in air.
Answer : (a) 

Question. Assertion : Detergents are better cleansing agent than soaps.
Reason : It is because they work with soft water.
Answer : (c) 

Question. Assertion : General formula of alkanes is CnH2n + 2.
Reason : It is because they are saturated compounds.
Answer : (b) 

Question. Assertion : Hard water contains magnesium and phosphate salts.
Reason : It is because they are easily available in water.
Answer : (d) 

Question. Assertion : Ethane is the homologous of methane.
Reason : It is because it differs by CH3 group.
Answer : (b) 


Creating Based Questions

Question. Covalent bonds formed as a result of sharing of electron pairs between two atoms are strong in nature. But the covalently bonded molecules have low melting and boiling points compared to the ionic molecules. What is the reason behind such behaviour ?
Answer : Covalent bond is formed by equal sharing of valence electrons between two atoms, hence there is no charge separation along the bond formed and they have weak intermolecular forces. Due to this, covalently bonded molecules have low melting and boiling points.

Question. Why are the unsaturated carbon compounds more reactive than saturated carbon compounds?
Answer : Unsaturated carbon compounds have double or triple bonds between carbon atoms, which are less stable than the sigma bonds and hence more reactive than saturated compounds which have single bond.

Question. Which property of ethanol enables its use in preparation of certain types of medicines ?
Answer :  Ethanol is a very efficient solvent hence, it is used as a base for many medicines which are prepared in suspension or solution form.

Question. A shiny soft metal is put in a test tube containing ethanol, a reaction takes place within the test tube with evolution of bubbles. The gas is collected and exposed to a burning candle. The gas burns with a pop sound.
(i) Name the shiny soft metal.
(ii) Name the gas evolved as a result of chemical reaction.
(iii) Write the equation for chemical reaction.
Answer : 
(i) The shiny soft metal is sodium.
(ii) Hydrogen gas is evolved as a result of the reaction between sodium metal and ethyl alcohol. The presence of hydrogen gas can be tested by bringing a burning candle near a gas filled bubble, hydrogen gas burns with a pop sound.
(iii) The reaction equation can be given as :
2Na(s) + 2C2H5OH(l)   →   2C2H5ONa + H2(g)

Question : Question.Give a chemical test to distinguish between ethanol and ethanoic acid.
Answer : Ethanoic acid is a two-carbon containing compound with a carboxylic acid functional group. Addition of sodium hydrogen carbonate solution to the ethanoic acid leads to evolution of bubbles from the reaction mixture. The gas evolved is carbon dioxide. Whereas, addition of sodium hydrogen carbonate solution to ethanol does not give any bubbles.

Question : Question. What is the product formed when a hydrocarbon is oxidised completely in presence of oxygen ?
What is the name of reaction ?
Answer : A hydrocarbon is oxidised completely to give carbon dioxide and water along with heat and light. The reaction is known as combustion.

Question. Why do the burners of gas or kerosene stoves contain small holes ?
Answer : The small holes present in burners of gas or kerosene stoves are actually small inlets for air to allow sufficient oxygen rich air mixture which ends up in giving clean blue flame.

Case study question

1. Water is a simple molecule consisting of one oxygen atom bonded to two different hydrogen atoms. Because of the higher electronegativity of the oxygen atom, the bonds are polar covalent (polar bonds). The oxygen atom attracts the shared electrons of the covalent bonds to a significantly greater extent than the hydrogen atoms. The molecule has a bent structure, the H—O—H bond angle is about 105°.

Question : What is the shape of water molecule?
(a) Linear
(b) Trigonal planar
(c) Bent
(d) Octahedral

Answer : C

Question : The correct electron dot structure of a water molecule is
(a) H O O
(b) H O O
(c) H O H
(d) H O O

Answer : C

Question : Which of the following statement is true regarding the electronegativity of atoms in water molecule?
(a) Hydrogen is more electronegative than oxygen
(b) Hydrogen is less electronegative than oxygen
(c) Electronegativity is same in Hydrogen and oxygen
(d) Hydrogen and oxygen do no show significant electronegativity in water

Answer : B

Question : The H—O—H bond angle in water molecule is
(a) 109.5°
(b) 180°
(c) 90°
(d) 105.0°

Answer : D

Question : Select the correct type of bonding in a water molecule
(a) Ionic Bonding
(b) Covalent Bonding
(c) Hydrogen Bonding
(d) None of these

Answer : B

 

Very Short Answers 

 
Question : Name the organic acid present in red ants. 
Answer : The acid produced by ants is called formic acid.   
 
Question : Name the functional groups present in the following compounds.
i. CH3COCH2CH2CH2CH3
ii. CH3CH2CH2COOH
iii. CH3CH2CH2CH2CHO
iv. CH3CH2OH
Answer : i. The functional group present in given compound is Ketone,
A-7
ii. The functional group present in given compound is Carboxylic acid, -COOH
iii. The functional group present in given compound is Aldehyde, -CHO
iv. The functional group present in given compound is Alcohol, -OH
 
Question : What is the common name of ethanoic acid? How ethanoic acid is different from vinegar? Give the use of vinegar in our daily life. 
Answer :  Ethanoic acid (CH3COOH) is commonly known as acetic acid. The dilute solution of acetic acid in water (6-8%) is known as vinegar. The vinegar is used for preserving food sausage, pickles, etc. 
 
Question : What are the various ways in which an atom can achieve the noble gas configurations? 
Answer : An atom can achieve the noble gas configurations by transfer of electrons to/from the other atom(s) or by sharing of electrons with other atom(s).

Question : What is homologous series?
Answer : It is a series of organic compounds having same functional group and similar chemical properties

Question : The molecular formula of two members of a homologous series are C3H4 and C6H10. Write the molecular formula of a member of this family with five carbon atoms in a molecule.
Answer : C5H8

Question : An alkene ‘P’ has three carbon atoms and an alcohol ‘Q’ has four carbon atoms. Write the formulae of P and Q.
Answer : ‘P’ is CH3–CH=CH2, ‘Q’ is CH3CH2CH2CH2OH

Question : Write the general formula of alkenes. Write the name of the simplest alkene.
Answer : CnH2n, Ethene is simplest alkene

Question : Write the next homologue of each of the following: (i) C2H4, (ii) C4H6
Answer : (i) C3H6, (ii) C5H8

Question : Write the molecular formula of benzene and state the number of double bonds in its structure.
Answer : C6H6, It has three double bonds

Question : Write the molecular formula of alcohol derived from butane.
Answer : C4H9OH or CH3CH2CH2CH2OH (Butan-1-ol)

Question : Write the molecular formula of an alkyne containing 10 atoms of hydrogen.
Answer : C6H10

Question : Write the name and molecular formula of the fourth member of alkane series. 
Answer : C4H10, Butane (CH3CH2CH2CH3)

Question : Write the name and formula of second member of homologous series with general formula CnH2n+2
Answer : C2H6, Ethane

Question : Write the name and formula of second member of homologous series having general formula CnH2n–2.
Answer : C3H4, Propyne

 

Short Answers

 
Question : Explain giving chemical equation, how are esters prepared? Specify any one property and one use of esters. 
Answer :  Ethyl ethanoate which is a ester of ethanoic acid and ethanol.
Ma-18
 
The process is called esterification.
 
 
Question : Name the following compounds. 
A
A-1
Answer : i. Propanone (CH3COCH3)
ii. Butanal (C3H7CHO)
iii. Methanoic acid (HCOOH)
 
 
Question : Why is the conversion of ethanol to ethanoic acid an oxidation reaction? 
Answer :  During the conversion of ethanol to ethanoic acid 1 oxygen atom is added to the ethanol to convert ethanoic acid. Addition of oxygen is nothing but oxidation. Hence, the conversion of ethanol to ethanoic acid called an oxidation reaction.
Ma-19 
 
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 relation between the two in the language of science. 
Answer :   An aldehyde as well as a ketone both are different functional groups and can be represented by the same molecular formula, say C3H6O.
Their structures are as follows:
A-6
 
Such compounds with identical molecular formula but different structures are called structural isomers. Where number of atoms of each type remain same only the arrangement changes. 
 

Question. What is a homologous series? Explain with an example.
Answer : A homologous series can be defined as a family of organic compounds having the same functional group, similar chemical properties and the successive members of which
differ by a – CH2 group or 14 mass units. For example, CH3OH (methanol), CH3CH2OH (ethanol), CH3CH2CH2OH (propanol), CH3CH2CH2CH2OH (butanol), etc. constitute a homologous series of alcohols. They have the same functional group, i.e., —OH (hydroxyl). Since they have the same functional group, they show similar chemical properties. The difference between any two successive members is a —CH2 group and 14 mass units. Their physical properties such as melting point and boiling point increase as the molecular mass increases. Their solubility in water, however, decreases with increase in molecular mass.

Question. What are covalent bonds? Show their formation with the help of electron dot structure of methane. Why are covalent compounds generally poor conductors of electricity?
Answer : Covalent bonds are those bonds which are formed by sharing the valence electrons between two atoms. Electron dot structure of methane is shown in the figure. Covalent compounds are generally poor conductors of electricity because they do not have free electrons or ions.

Question. Taking a suitable example show the formation of a molecule bonded by triple covalent bond.
Answer : Nitrogen (atomic number 7) atom has an electronic configuration of K L 2 5 indicating the presence of 5 electrons in the outermost L-shell. Thus, each nitrogen atom needs three electrons to attain the nearest stable noble gas electronic configuration of neon gas. So, two nitrogen atoms combine together by sharing 3 electrons each to form a molecule of nitrogen.

Question. Why are most carbon compounds poor conductors of electricity?
Answer : Due to catenation, carbon forms covalent bonds with the constituent elements in the carbon compounds, hence it does not have mobile electrons and carbon compounds do not dissociate themselves into ions and hence, they are poor conductor of electricity.

Question. What are covalent compounds? Why are they different from ionic compounds? List their three characteristic properties.
Answer : Covalent compounds are those compounds which are formed by sharing of valence electrons between the atoms e.g., Hydrogen molecule is formed by mutual sharing of electrons between two hydrogen atoms. They are different from ionic compounds as ionic compounds are formed by the complete transfer of electrons from one atom to another e.g., NaCl is formed when one valence electron of sodium gets completely transferred to outer shell of chlorine atom. The characteristic properties of covalent compounds are :
(i) They are generally insoluble or less soluble in water but soluble in organic solvents.
(ii) They have low melting and boiling points.
(iii) They do not conduct electricity as they do not contain ions.

Question. Why are carbon and its compounds used as fuels for most applications?
Answer : Carbon burns in oxygen or air to form carbon dioxide gas. The reaction is highly exothermic. That is why different forms of coal are used as fuels. The most important compounds of carbon are hydrocarbons. Just like carbon, hydrogen also readily burns in oxygen or air to form water producing heat. The hydroca rbon methane (CH4) is a constituent of natural gas. Propane (C3H8) and butane (C4H10) are present in liquid petroleum gas (L.P.G.). Petrol and kerosene also contain different hydrocarbons. Therefore, these are used as fuels.

Question. What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur? (Hint : The eight atoms of sulphur are joined together in the form of a ring).
Answer : The atomic number (Z) of sulphur is sixteen and its electronic configuration is 2, 8, 6. The sulphur atom has six valence electrons. The chemical formula of sulphur molecule
is S8. Each sulphur atom is linked to similar atoms on either sides by single covalent bonds and thus, completes its octet.
The molecule is in the form of a ring also represented by crown shape.

Question. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?
Answer : (i) Catenation : Carbon has the unique property of self linking which is known as catenation. In fact, any number of carbon atoms can be linked to one another by covalent
bonds. This is on account of the stability of C — C bonds since the size of the carbon atom is quite small.
(ii) Linking of carbon with other atoms : Carbon is tetravalent in nature and can readily unite with atoms like hydrogen, oxygen, nitrogen, sulphur, etc. by electron sharing.

Question. Consider the molecular models of the two organic compounds shown below: 
CBSE Class 10 Science Chemistry Carbon and its compounds Assignment
(a) Name the homologous series that compounds I and II belong to and give its general formula.
(b) Write the molecular formulae of next homologue of both compounds I and II.
Answer : (a) Alkenes with general formula CnH2n.
(b) Next homologue of compound (I) is C3H6 i.e., propene and next homologue of compound (II) is C5H10 i.e., pentene.

 

Long Answers

 
Question : Name the following compounds. 
Answer :  According to the question, Given compounds are
 
Ma-20
 
Ma-21 
 
 
Question : What are alcohols? What is its general formula? Give the names and molecular formula of first three members of the homologous series of alcohols. 
Answer : The organic compounds containing the hydroxyl or alcoholic group (–OH) as the functional group are called alcohols. These are obtained by replacing one hydrogen atom of an alkane by –OH group. For example,
A-5
 

Question. What happens when (write chemical equation in eachcase) 
(a) ethanol is burnt in air ?
(b) ethanol is heated with excess conc. H2SO4 at 443 K ?
(c) a piece of sodium is dropped into ethanol ? 
Answer :
(a) CH3CH2OH + 3O2   → 2CO2 + 3H2O + Heat + light
                        Conc H2SO4
(b) CH3CH2OH       →                CH2 = CH2 + H2
                          Δ 443k 
(c) 2CH3CH2OH + 2Na → 2CH3CH3ONa + H2

Question. Explain esterification reaction with the help of a chemical equation. Describe an activity to show esterification.
Answer :
The reaction of carboxylic acid with alcohol forms an ester. This process of formation of ester is called esterification.
CH3COOH + CH3CH2OH    →   CH3COOCH2CH3 + H2O
Activity :
(a) Take 1 ml of ethanol and 1 ml of glacial acetic acid in a boiling tube and mix the contents well.
(b) Add few drops of conc. H2SO4 to it.
(c) Warm the contents on a water bath for a few minutes.
(d) Now pour the solution in a beaker containing 20-50 ml of water. 
(e) A sweet fruity smell indicating formation of an ester is observed.

Question. Two carbon compounds X and Y have the molecular formula C4H8 and C5H12 respectively. Which one of these is most likely to show addition reaction ? Justify your answer. Also give the chemical equation to explain the process of addition reaction in this case.
Answer :
X = C4H8 is an alkene.
Y = C5 H12 is an alkane.
X being an alkene i.e., butene is unsaturated compound and will show addition reaction as they have free electrons for bonding.
CH3CH2CH = CH2 + H2  Pd/Ni→   CH3CH2CH2CH3
CH3CH = CHCH3 + Cl    hv→     CH3ClCHClCHCH3

Question. Two carbon compounds X and Y have the molecular formula C3H6 and C4H10 respectively. Which one of the two is most likely to show addition reaction ? Justify your answer. Also give the chemical equation to explain the process of addition reaction in this case.
Answer :
C3H6 is propene i.e., unsaturated hydrocarbon. C4H10 is butane i.e., saturated hydrocarbon. Thus, propene being unsaturated shows addition reaction.
CH3 — CH = CH2 + Cl2   →  CH3CH — CH2Cl
                                            |
                                           Cl

Question. Why does micelle formation takes place when soap is added to water ? Will a micelle form in other solvents such as ethanol also ? 
Answer : Soap may be represented by the formula RCOONa where R is an alkyl group which represents long chain of carbon with fifteen or more atoms. Oil drops containing dirt particles and water do not mix. Soap helps in their mixing by reducing interfacial tension or friction. Actually it forms a sort of bridge between oil drops and water in which the alkyl portion (hydrophobic end) point towards oil drop while other portion (hydrophilic end) is directed towards water. This is known as micelle formation. Thus, soap helps in the formation of a stable emulsion between oil and water. Ethanol and other similar solvents which are of organic nature do not help in micelle formation because soap is soluble in them.

Question. Catenation is the ability of an atom to form bonds with other atoms of the same element. It is exhibited by both carbon and silicon. Compare the ability of catenation of the two elements. Give reasons.
Answer : Carbon has the maximum capacity of catenation. The reason for this is the smaller size of of carbon which makes the C–C bonds strong. The size of silicon is greater than Carbon. This makes Si—Si bonds comparatively weaker than C – C bond.

Question. (a) What is the atomic number of carbon. Write its electronic configuration.
(b) What type of chemical bonds re formed by carbon ? Why ?
(c) Name the three allotropic forms of carbon.
Answer :
(a) The atomic number of carbon is 6. Its electronic configuration is 2, 4.
(b) Carbon forms covalent bonds because it can achieve the inert gas electron arrangement only by sharing of electrons.
(c) Diamond, graphite and buckminster fullerene.

Question. (a) Give the general name of the class of compounds having the general formula CnH2n–2. Write name of the first member of this homologous series.
(b) The general formula of a homologous series of carbon compounds is CnH2n. Write the molecular formulae of the second and fifth members of the series.
(c) Write the molecular formulae of the third and fourth members of homologous series of carbon compounds represented by the general formula CnH2n+2.
Answer :
(a) Alkynes, CnH2n–2
First member : Ethyne : C2H2
(b) Second member : C3H6
Fifth member : C5H12
(c) Third member : C3H8
Fourth member : C4H10

Question. Preetam and Satnam were revising the chapter on Carbon and its compounds. Preetam said, “It is quite amazing that diamond and graphite are both allotropes of carbon but the two have completely different properties. While diamond is the hardest material, graphite is soft”.
(a) What is the cause of different nature of these two substances ?
(b) What is the core of lead pencils ?
Answer :
(a) The difference in nature of the two substances is due to structure of the two allotropes. In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three dimensional structure. In graphite, each carbon atom is bonded to three other carbon atoms in the same plane, giving a hexagonal array. The fourth valency is satisfied by weak bonding between carbon atoms in one plane with the corresponding atoms in the other planes above and below a particular plane.
(b) Lead pencil is a monomer. Actually it is graphite which the core of the pencil is made of.

Question. An organic compound A having the molecular formula C3H8O is a liquid at room temperature. The organic liquid A reacts with sodium metal to evolve a gas which burns causing a little explosion. When the organic liquid A is heated with concentrated sulphuric acid at 170°C, it forms a compound B which decolourises bromine water. The compound B adds on one molecule of hydrogen in the presence of Ni as catalyst to form compound C which gives substitution reactions with chlorine.
(a) What is compound A ?
(b) What is compound B ?
(c) What type of reaction occurs when A is converted into B ?
(d) What is compound C ?
(e) What type of reaction takes place when B is converted into C ?
Answer :
(a) A is propanol, CH3–CH2–CH2OH.
(b) B is propene, CH3CH = CH2.
(c) Dehydration reaction.
(d) C is propane, CH3CH2–CH3.
(e) Addition reaction.

Question. Give reasons :
(a) Why is pure ethanoic acid known as glacial aceticacid ?
(b) Why is ethanol used as antifreeze ?
(c) What is gasol ?
Answer :
(a) Pure ethanoic acid has a low freezing point. It freezes and looks like glaciers.
(b) Ethanol mixed with water freezes at temperatures lower than water. Thus, a mixture of water and ethanol is used in radiators of cars in cold countries.
(c) Gasol is a mixture of petrol and alcohol.

Question. What happens when hydrogen is added to a vegetable oil in the presence of nickel ? Name the reaction and write one difference between the physical property of the vegetable oil and the product obtained in this reaction. Write the role of nickel in this reaction.
Answer : When hydrogen is added to a vegetable oil in the presence of nickel the vegetable oil is converted into saturated fat. The reaction is called hydrogenation reaction. Vegetable oil is liquid whereas saturated fat is solid at room temperature. Nickel acts as the catalyst in this reaction.

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 of compounds are having covalent bonds.
Ionic compounds are formed due to transfer of electrons from one atom to another while covalent compounds are formed by the sharing of electrons :
The two properties of covalent compounds are :
(a) Covalent compounds are poor conductors of electricity
(b) They have low melting and boiling point.

Question. Ethanoic acid reacts with absolute ethanol in the presence of Conc. H2SO4 to form a compound.
(a) Write the smell and class of compounds to which this compound belong.
(b) Write the chemical equation for the reaction and state the role of Conc. H2SO4 in the reaction.
(c) Write one use of the product of this reaction.
Answer :
(a) Pleasant or fruity smell and it belongs to Esters.
                                      conc.H2SO4
(b) CH3COOH + C2H5OH       →           CH3COOC2H5          
                                         −H2O
Conc. H2SO4 acts as a catalyst or dehydrating agent.
(c) Used in perfume industry and as flavouring agent.

Question. What is a homologous series of carbon compounds ?Write the formula of the fourth and fifth member of a homologous series having general formula CnH2n + 1 OH. List two differences in physical properties found in the two consecutive members of a homologous series. 
Answer : A group of organic compounds having the same functional group and similar structures in which two
successive members differ by –CH2 group. C4H9OH and C5H11OH.
(a) They differ by a mass of 14 u and show gradation in properties.
(b) Their boiling point increases with increase in molecular mass.

Question. Complete the following chemical equations :
(a) CH3COOH + Na2CO3
(b) CH3COOH + NaOH →
(c) CH3COOC2H5 + NaOH →
Answer :
(a) CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2
(b) CH3COOH + NaOH → 2CH3COONa + H2O
(c) CH3COOC2H5 + NaOH → CH3COONa + C2H5OH

Question. Give reason why carbon can neither form C4+ cations nor C4– anions, but forms covalent compounds which 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. While it 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 and the Inter molecular forces of attraction are weak, hence they have low melting and boiling points.

Question. Name two oxidising agents that are used for the conversion of alcohols to acids. Distinguish between ethanol and ethanoic acid on the basis of (a) litmus test, and (b) reaction with sodium hydrogen carbonate.
Answer : Alkaline KMnO4 and Acidified KrCr2O7 are used as oxidising agents to convert alcohols to acids.
(a) Ethanol does not affect litmus paper whereas Ethanoic acid turns blue litmus red.
(b) Ethanol does not react with NaHCO3 whereas Ethanoic acid gives brisk effervesence with the evolution of colourless gas CO2.

Question. An organic compound ‘P’ is a constituent of wine. ‘P’ on reacting with acidified K2Cr2O7 forms another compound ‘Q’. When a piece of sodium is added to ‘Q’ a gas ‘R’ evolves which burns with a pop sound. Identify P, Q and R and write the chemical equations of the reactions involved.
Answer : P — Ethanol, Q — Ethanoic acid, R — Hydrogen.
CH3CH2OH        Acidified K2Cr2O7→     CH3COOH
2CH3COOH + 2Na → 2CH3COONa + H2

Question. A student is studying the properties of acetic acid in his school laboratory. List two physical and two chemical properties which he must observe and note in his record book.
Answer :
Physical properties :
(a) Smell like vinegar,
(b) Colourless liquid.
Chemical properties :
(a) turns blue litmus red,
(b) gives brisk effervescence with sodium carbonate.

Question. (a) What is a homologous series ? Explain with an example.
(b) State two characteristics of a homologous series.
(c) The molecular formula of an organic compound is C18H36. Name its homologous series.
(d) Select the hydrocarbons which belong to the same homologous series. Give the name of each series. CH4, C2H2, C2H4, C2H6, C4H10, C3H4, C3H6
(e) What is meant by ‘heteroatom’ ? Give examples. Write the names and formulae of two organic compounds containing different heteroatoms.
Answer :
(a) A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by CH2 group. Example of homologous series : All the alkanes have similar structures with single covalent bonds and show similar chemical properties, so they can be grouped together in the form of a homologous series. Homologous series of alkanes : Methane, CH4; Ethane, C2H6; Propane, C3H8; Butane, C4H10; Pentane, C5H12.
(b) (i) All the members of the homologous series can be represented by the same general formula.
(ii) Any two adjacent homologues differ by 1 carbon atom and 2 hydrogen atoms in their molecular formulae.
(c) Alkene, CnH2n
(d) Alkanes: CH4; C2H6 ; C4H10
Alkenes : C2H4, C3H6
Alkynes : C2H2, C3H4
(e) In an organic compound, any atom other than carbon and hydrogen is called a heteroatom.
Example : Chlorine (Cl), Bromine (Br), Oxygen (O)
Chloromethane – CH3Cl and methanol –CH3OH.

Question. Explain the given reactions with the examples :
(a) Hydrogenation reaction
(b) Oxidation reaction
(c) Substitution reaction
(d) Saponification reaction
(e) Combustion reaction
Answer :
(a) Unsaturated hydrocarbons add hydrogen in the presence of nickel catalyst to give saturated hydrocarbons.
R2C = CR2 + H   Ni→    R2C — CR4
                                          |      |
                                          H     H
(b) Ethanol is oxidised to ethanoic acid in the presence of alkaline KMnO4 on heating.
                     Alc. KMnO4
CH3CH2OH      Hert →       CH3COOH
(c) In the presence of sunlight, chlorine is added to hydrocarbons.
CH4 + Cl2    hv→    CH3Cl + HCl
(d) CH3COOC2H5 + NaOH → CH3COONa + C2H5OH Ester Used in the preparation of soap.
(e) Most carbon compounds release a large amount of heat and light on burning
CH4 + 2O → 2H2O + Heat and light

Question. (a) Write a chemical test to distinguish between saturated and unsaturated hydrocarbons.
(b) Name the products formed when ethane burns in air. Write chemical equation for the reaction showing various types of energies liberated.
(c) Write the reaction between methane and chlorine in the presence of sunlight. Why is this reaction considered a substitution reaction ?
Answer :
(a) Bromine water test is used to differentiate between the unsaturated compounds (like alkanes and alkynes) and the saturated compounds. For this purpose, bromine is used in the form of bromine water. Bromine water has a red-brown colour due to the presence of bromine in water. When bromine water is added to an unsaturated compound, then bromine gets added to the unsaturated compound and the red-brown colour of bromine water is discharged. So, if an organic compound decolourises bromine water, then it will be an unsaturated hydrocarbon (containing a double bond or a triple bond,) but saturated hydrocarbon (alkenes) do not decolourise bromine water.
(b) Carbon dioxide (CO2) and Water (H2O)
2C2H6 + 7O2 → 4CO2 + 6H2O + Heat + Light
(c) CH4 + Cl2   sunlight→ CH3Cl + HCl ; This reaction is considered a substitution because hydrogen atom is replaced by chlorine atom.

Question. What are esters ? How are esters prepared ? Write the chemical equation for the reaction involved. What happens when an ester reacts with sodium hydroxide ?
Write the chemical equation for the reaction and also state the name and use of this reaction. 
Answer :
Esters : They are sweet-smelling organic compounds,with the general formula RCOOR’ (R and R’ are similar or dissimilar alkyl groups)
Preparation of ester : Esters are prepared by esterification which is a reaction between carboxylic acids and alcohols in the presence of an acid.
For example, when ethanoic acid reacts with ethanol in the presence of an acid, ethyl ethanoate is formed. Ethyl ethanoate is an ester, and has a sweet smell.
CH3CH2OH   +   CH3COOH     Acid →   CH3COOCH2CH3            + H2O
Ehanol             Ethanoic acid                Ethyl ethanoate (Ester)     Water
Reaction with sodium hydroxide :
Ethyl acetate (an ester) reacts with sodium hydroxide (base) to form ethanol (alcohol) and ethanoic acid (carboxylic acid.)
CH3COOCH2CH3   NaOH→    CH3CH2OH + CH3COOH
Ethyl ethanoate                     Ethanol         Ethanoic acid
( Ester)
Thus, alcohol and carboxylic acid can be reclaimed from an ester by reacting it with an acid or a base. This reaction is used in the preparation of soaps and it is known as saponification reaction.

Question. What are micelles ? Why does it form when soap is added to water ? Will a micelle be formed in other solvents such as ethanol also ? State briefly how the formation of micelles help to clean the clothes having oily spots.
Answer :
Soap molecules have two ends – at one end is the hydrocarbon chain which is water repellent, whereas at the other end there is the ionic part which is water soluble end. When soap is dissolved in water it forms a group of many molecules, known as micelle. These micelles are formed because their hydrocarbon chains `come together and the polar ends are projected outwards. Micelle formation in ethanol will not occur because the hydrocarbon chain end of the soap will dissolve in ethanol. Soaps in the form of micelle are able to clean dirty clothes having oily spots, as the oily dirt is collected in the centre of the micelle, which forms an emulsion in water and on rinsing, the water washes away the micelles with dirt attached to them.

 

1 MARKS QUESTIONS

Question : What is the unique property of carbon atom? How is this property helpful to us?

Question : Why is graphite a good conductor of electricity but diamond is a non-conductor of electricity?

Question : Write the electron dot structure for: 

(a) Ammonia (NH3)

(b) Nitrogen (N2)

(c) Ethyne (C2H2)

(d) Carbon dioxide (CO2)

(e) Benzene (C6H6)

(f) Cyclopentane

Question : The molecular formula of A is C10H18 and B is C18H36.Name the homologous series to which they belong. 

Question : Classify the following compounds as alkanes, alkenes and alkynes.

C2H4 , C3H4 , C4H8 , C5H12 , C5H8 , C3H8

2 MARKS QUESTIONS

Question : Why carbon forms compounds by sharing of electrons and not by the formation of ions?

Question : State the meaning of functional group.Write the functional group present in (a)Ethanol and(b) Ethanoic acid and also draw their structures.

Question : Draw the structures of the following compounds :
(i) 2-Bromopentane (ii) 2-methylpropane (iii) Butanal (iv) 1-Hexyne

Question : A hydrocarbon molecule has 3 carbon atoms. Write down its molecular formulae if it is an
(i) alkene, (ii) alkyne

Question : How would you name the following compounds :
(i) CH3-CH2-CHO (ii) CH3-CHOH-CH3
(iii) CH3-CH2-CH2-CH(CH3)-CH3(iv) CH3-CH2-CH=CH2

Question : The general formula of a homologous series of carbon compounds is CnH2n. Write the structures and IUPAC names of the second and fourth member of this series.

Question : Compare the ability of catenation of Carbon and Silicon. Give reasons.

Question : What is meant by hydration of ethene? What is the role of sulphuric acid in this reaction?
Explain with a chemical equation.

Question : Explain the cleansing action of water. . 

3MARKS QUESTIONS

Question : Complete the following equations. Also name the final products.
(a) CH3COOC2H NaOH →
(b) CH3COOH + NaHCO3
(c) CH3COOH + C2H5OH Conc. H2SO4
(d) C2H5OH + Na
(e) CH3COOH + NaOH

Question : An organic compound with molecular formula C2H4O2 produces brisk effervescence on addition of sodium carbonate/bicarbonate.
(a) Identify the organic compound.
(b) Name the gas evolved. How will you test this gas?
(c) Write a chemical equation for the above reaction.
(d) List two important uses of the above compound.

Question : What is an oxidising agent? Name two oxidising agents which can oxidise ethanol to ethanoic acid.
Write the equation of the reaction involved.

Question : How is that we can use detergents for washing clothes even when the water is hard, but not soap ?
What change has been made in the composition of the detergents to make them biodegradable ?

Question : Differentiate between soaps and detergents.

Question : Give reason:
(a) A mixture of oxygen and ethyne is burnt for welding and not a mixture of ethyne and air.
(b) Soaps do not work well with hard water.
(c) Carbon compounds do not conduct electricity? 

Question : (a) What is a homologous series of a substance?
(b) In an organic compound, which parts largely determine its physical and chemical properties?
(c) An organic compound burns with a sooty flame.Is it a saturated or an unsaturated hydrocarbon?
Give reason.

Question : Value based Question:
Most of the children of a school in a village bring parantha and pickle in their tiffin. These children
do not share their food with anyone. Some children bring chapati, fruit , curd, salad, vegetable. These
children share their food with each other. ?
a) Which acid is present in curd and vinegar, used in pickle ?
b) What class of compound should be present in our diet ?
c) Which group of children bring healthy food ? Give two benefit of this food.
d) Which group of children bring unhealthy food ? Give two harmful effects.
e) Which group of children have better value system and why ?

Chapter 01 Chemical Reactions and Equations
CBSE Class 10 Science Chemical Reactions and Equations Assignment

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