CBSE Class 10 Science Carbon And Its Compounds Worksheet Set C

Question. Bromine reacts with saturated hydrocarbon at room temperature in the
(a) absence of sunlight
(b) presence of water
(c) presence of sunlight
(d) presence of hydrochloric acid
Answer : C

Question. The upper and lower homologue of C₂H₅OH are respectively
(a) methyl alcohol and butyl alcohol
(b) ethyl alcohol and propyl alcohol
(c) butyl alcohol and propyl alcohol
(d) propyl alcohol and methyl alcohol
Answer : D

Very Short Answer Questions

Question. What is a hydrocarbon?
Answer : It is a compound of hydrogen and carbon.

Question. Name two types of hydrocarbon.
Answer : Hydrocarbon – Saturated and unsaturated.

Question. What is catenation?
Answer : Carbon has the unique ability to form bonds with the other atoms of carbon which gives rise to large molecules. This property of self linking is called catenation.

Question. Why covalent compounds have low melting and boiling points?
Answer : As the bond is formed by sharing of electrons between two atoms. Intermolecular forces are small between the covalent compounds. These bonds break easily.

Question. Define catalyst.
Answer : Catalyst are substances that cause a reaction with a change in rate of reaction, without itself undergoing any change.
Example: Micelle acts as a catalyst to convert unsaturated hydrocarbon into saturated hydrocarbon.

Question. Give the full form of IUPAC.
Answer : IUPAC → International Union of Pure and Applied Chemistry.

Question. How can we convert CH₃CH₂OH into C₂H₄ ?
Answer : By adding conc. sulphuric acid into it which acts as dehydrating agent and removes water from it.

Question. What is the melting point of acetic acid?
Answer : M.P. = 290 K.

Question. How can you convert ethene into ethane?
Answer : By adding hydrogen to ethene in the presence of a catalyst.

Question. What is esterification reaction?
Answer : The reaction in which alcohol reacts with carboxylic acid to produce a new compound called ester is called esterification.

Question. What is isomerism?
Answer : A property in which a compound can exist in different structural formula but its molecular formula remains the same.

Question. What is hydrophilic?
Answer : The substance showing attraction towards water is called hydrophilic.

Question. ‘‘Saturated hydrocarbons burn with a blue flame while unsaturated hydrocarbons burn with a sooty flame’’. Why?
Answer. An unsaturated hydrocarbon has high concentration of carbon, which does not get oxidised by the atmospheric oxygen. Thus, unburnt carbon appears in the form of soot and hence the flame is sooty.

Question. Write the next higher homologue of the following : (i) C₃H₆ (ii) C5H₈
Answer. (i) C₄H₈ (ii) C₆H₁₀

Question. Write the name and structure of an aldehyde with 4 carbon atoms.
Answer. C₃H₇ CHO (Butanal)

Question. Draw the electron dot structure of ethane (C₂H₆).
Answer. 

Question. Draw the structure of pentanal (C₄H₉CHO).
Answer.

Question. Name the functional group present in each of the following compounds.

Answer. C₃H₇OH — Alcoholic group

Question. Draw the structure of ethene molecule (C₂H₄).
Answer.

​
 

Question. (a) Name the functional group present in propanal (C₃H₆O).
Answer. Aldehyde group

(b) Name the fourth (4th) member of alkene series.
Answer. Pentene

Question. (a) Name the type of reaction represented by the following equation :

Answer. Esterification

(b) Draw the structure of ethanol molecule.
Answer.

Question. Why is the conversion of ethanol to ethanoic acid considered an oxidation reaction?
Answer. Conversion of ethanol to ethanoic acid is considered an oxidation reaction since it involves:
(i) addition of oxygen to the ethanol molecule
(ii) removal of hydrogen from the ethanol molecule.

Question. (a) Draw the structure of the simplest ketone.
Answer.

Question.(b) Draw the structure of CH₃COOH molecule.
Answer.

Question. (a) Name the compound formed when ethanol is warmed with ethanoic acid in the presence of few drops of concentrated. H2SO4.
Answer. Ethyl ethanoate (an ester)

Question.(b) Write a chemical equation to represent the reaction of ethanol with acidified solution of potassium dichromate.
Answer.

Question. (a) What happens when a small piece of sodium is dropped into ethanol?
Answer. Sodium reacts with ethanol to form sodium ethoxide and liberates hydrogen gas.

Answer. Acetone or propanone

Question. Why does carbon form compounds mainly by covalent bonding?
Answer. Carbon has four valence electrons. Thus, it is not in a position to donate/accept four electrons so as to acquire a stable neon gas like structure. Thus, in order to enter into a chemical reaction,it shares its valence electrons with other elements.

Question. (a) What would be observed on adding a 50% solution of alkaline potassium permanganate drop by drop to some warm ethanol taken in a test tube?
(b) Write the name of the compound formed during the chemical reaction.
Answer. (a) The pink colour of potassium permanganate would be discharged.
(b) Ethanoic acid.

Question. (a) How would you distinguish experimentally between an alcohol and a carboxylic acid on the basis of a chemical property?
Answer. Ethanol does not react with sodium carbonate. However, carboxylic acid reacts with sodium carbonate with the liberation of carbon dioxide gas which turns limewater milky.

(b) Name the gas evolved when ethanoic acid is added to sodium carbonate. How would you prove the presence of this gas?
Answer. Carbon dioxide gas.
The gas when passed through limewater turns the limewater milky.

Question. What is a functional group in a carbon compound. Identify the functional group present in CH₃COOH and C₂H₅OH.
Answer. An atom or a group of atoms which gives the same characteristic properties to a compound is called a functional group.
Functional group in : CH₃COOH — Carboxylic acid group
C₂H₅OH — Alcoholic group

Question. (a) name the compound CH₃CH₂OH and identify its functional group.
Answer. Ethyl alcohol
Alcoholic group.

(b) What is the difference in the molecular formula of any two consecutive members of a homologous series of organic compounds?
Answer. CH₂

Question. Why are covalent compounds generally poor conductors of electricity?
Answer. Covalent compounds are formed by the sharing of valence electrons. As such they do not have cations or anions which could migrate to the opposite poles of an electrolytic cell. Thus, they do not conduct electric current.

Question. Write the names of the functional groups in :

Answer. (i) Ketonic group (ii) Aldehydic group

Short Answer Questions

Question. What is an homologous series? Explain with an example.
Answer : A homologous series is a series of carbon compounds that have different numbers of carbon atoms but contain the same functional group.

 

II. Distriction based on chemical properties

(i) Action with sodium hydrogen carbonate: On adding a small amount of sodium hydrogen carbonate to ethanoic acid, carbon dioxide gas is evolved with brisk effervescence. However, no such reaction noticed in case of ethanol.

(ii) Action with caustic alkalies Ethanoic acids reacts with both sodium hydroxide (NaOH) and potassium hydroxide (KOH) to form corresponding salt and water. Ethanol fails to react with either of these.

 

Question. Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Answer : A soap is a sodium or potassium salt of long chain fatty acids. It has one polar end and one non-polar end. The polar end is hydrophilic in nature i.e., this end is attracted towards water. The non-polar end is hydrophobic but lyophilic, i.e., it is attracted towards hydrocarbons. When soap is added to water, soap molecules arrange themselves in a cluster to keep the non- polar portion out of water such that the non-polar ends are in the interior of the cluster and the polar ends are on the surface of the cluster. Since the dirt present on clothes is organic in nature and insoluble in water, the hydrophobic ends of the clusters attach themselves to the dirt. This cluster formation in which the dirt is entrapped is the micelle. Micelle formation does not occur in alcohol because the alkyl chain of soap becomes soluble in alcohol.

Answer : Carbon burns in oxygen (air) to form carbon dioxide and water.

During this reaction a large amount of heat and light are released. Further, once ignited carbon and its compounds keep on burning without the requirement of additional energy. Hence, they are used as fuels.

 

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 : The by-product in soap industry is: 

 

Question : Which of the following is used for antifreeze mixture? 

a. C₂H₅OH

b. CH₃OH

c. HCHO

d. CH₃COOH

Answer : A 

Explanation: Ethanol ( C₂H₅OH) is used for antifreeze mixture. Antifreeze is an additive which lowers the freezing point of a water-based liquid. At room temperature, ethanol is a polar solvent and is used as antifreeze. 

 

Question : Statement A: Acetic acid freezes at 290K.

Statement B: Acetic is also called as glacial acetic acid. 

a. Statement A is true; Statement B is false.

b. Statement B is True; Statement A is false.

c. Both the statements A and B are true.

d. Neither Statement A nor Statement B is true.

Answer : C

Explanation: Freezing point of ethanoic acid is 17 °C (290 K). When ethanoic acid (acetic acid) is cooled, it freezes to form a colourless, ice-like solid. The solid looks like a glacier and hence pure ethanoic acid is also called glacial ethanoic acid (or glacial acetic acid). 

 

Question : The odour of ethanoic acid resembles which one of the following: 

a. Kerosene

b. Pungent

c. Rose

d. Vinegar

Answer : D

Explanation: The odour of ethanoic acid (CH₃COOH) resembles vinegar. A dilute solution of ethanoic acid in water is called vinegar. Vinegar contains about 5 to 8 % ethanoic acid.

 

Question : Which of the following statements are usually correct for carbon compounds?

A. They are good conductors of heat and electricity.

B. They are poor conductors of heat and electricity.

C. They have strong forces of attraction between their molecules.

D. They do not have strong forces of attraction between their molecules. 

a. B and C

b. All of these

c. B and D

d. A, B and D

Answer : C

Explanation: Carbon compounds are usually poor conductors of heat and electricity. Carbon compounds are covalent compounds that have been formed by the sharing of electrons. They do not have strong forces of attraction between their molecules. They have weak interactions between their molecules. This leads to low melting points and boiling points.

 

Very Short Answers

 

Question : What is the functional group of HCHO? 

Answer : The functional group of HCHO is -CHO. 

 

Question : Select saturated hydrocarbons from the following:
C₃H₆, C₅H₁₀, C₄H₁₀, C₆H₁₄, C₂H₄
Answer : Saturated hydrocarbons:
General formula= CnH²ⁿ⁺²
C₄H₁₀, C₆H₁₄

 

Question : Which of the following will turn blue litmus solution red? CH₃OH, CH₃COOH,CH₃COOCH_3.

Answer :  Blue litmus paper turns red under acidic conditions. CH₃COOH will turn blue litmus solution red because it is acidic.

 

Question : An organic compound is a constituent of beer, whisky and some cough syrup. It is produced by the fermentation of sugar. Identify the organic compound. 

Answer : Ethanol is a constituent of beer, whisky and some cough syrup. Ethanol is produced by the fermentation of sugar.

 

Question : Draw the structure of ethanoic acid molecule, CH₃COOH
Answer : Structure of ethanoic acid molecule:

 

Question :  What is a detergent? 

Answer :  Detergents are ammonium or sulphonate salts of long chain carboxylic acids. Detergent is also known as soapless soap. Soap cannot form lather in hard water. To overcome this problem, detergents were introduced.

 

Question : Give the IUPAC name of acetic acid and propyl alcohol.
Answer : Acetic acid – Ethanoic acid
Propyl alcohol – Propanol

Question : Why do soaps form scum when added to hard water?
Answer : Hard water contains carbonate and sulphate salts of magnesium or sodium ions which react with the soap molecule to form a compound which is insoluble in water. Hence soaps form scum with hard water.

Question : Give the IUPAC name and write the functional group present in vinegar.
Answer : Vinegar IUPAC name is acetic acid CH₃COOH
Functional group –COOH

Short  Answers Questions

Question : What is the reactive site in the given hydrocarbon? Write its name.
H₃C—CH₂—CH==CH—CH₃
Answer : The reactive site is at a place where double bond is present.
Name of the compound is 2-pentene.

Question : Name the peculiar/specific chemical property exclusive in case of saturated hydrocarbons and unsaturated hydrocarbons.
Answer : Saturated hydrocarbons show substitution reaction in which hydrogen atom gets substituted by other elements or atoms. Unsaturated hydrocarbons show addition reaction, in which hydrogen atom gets added across the double bond or triple bond of the compound.

Question : Why does carbon forms large number of compounds?
Answer : Carbon forms large number of compounds because of tetravalency and catenation property.
Tetravalency – Carbon has valency 4, to attain noble gas configuration carbon share its valence electrons with other elements like hydrogen, chlorine, etc.
Catenation – Carbon also shows the property of self-linking in which it forms long, branched or cyclic chains to form large number of compounds.

Question : How does ethanoic acid react with carbonates and hydrogen carbonates? Show it with the equation.
Answer : Ethanoic acid reacts with carbonates and hydrocarbonates to form salt, CO₂ and H₂O.
The salt formed is sodium acetate.
2CH₃COOH + Na₂CO₃ ⎯→ 2CH₃COONa + H₂O + CO₂
CH₃COOH + NaHCO₃ ⎯→ CH₃COONa + H₂O + CO₂

Question : A student burns a hydrocarbon in air and obtains sooty flame. Give two reasons for this observation.
Answer : Sooty flame could be obtained due to
(i) Incomplete combustion of saturated hydrocarbons.
(ii) Combustion of unsaturated hydrocarbon.

 

Question : i. Write the formula and draw the electron dot structure of carbon tetrachloride.

ii. What is saponification? Write the reaction involved in this process. 

Answer :

 

ii. The reaction of an ester in the presence of base to give sodium salt of carboxylic acid and alcohol is known as saponification and this process is used in the preparation of soap

 

Question : How many covalent bonds are there in a molecule of ethane, C₂H₆?
Answer : There are seven covalent bonds in a molecule of ethane:

 

 

Question : How would you name the following compounds? 

Answer :

 

 

 

Question : What are homologous series of carbon compounds? Write the molecular formula of two Consecutive members of homologous series of aldehydes.
Answer : A series of carbon compounds in which the same functional group substitutes for Hydrogen on a carbon chain is called homologous series. There is difference of –CH₂ in nThe molecular formula of two nearest compounds of a homologous series. Each such Series has same general molecular formula and has a general scientific name. There Is a difference of 14u in the molecular mass of two nearest compound of a series?
Members of homologous series of aldehydes:
H – CHO
CH₃ – CHO
C₂H₅ – CHO

 

 

Question : Mention four differences between saturated and unsaturated hydrocarbons. 

Answer : Difference between saturated and unsaturated hydrocarbons:

 

 

Question : Out of sodium chloride (NaCl) or methyl chloride (CH₃ Cl), which has higher melting and boiling points? Why? 

Answer :  The intermolecular forces are small in the covalent compounds.So, These bonds break easily. Hence, covalent compounds have low melting and boiling point.The intermolecular forces are small in the covalent compounds. These bonds break easily.

Hence, covalent compounds have low melting and boiling point.

Sodium chloride (Na⁺Cl^-) is an ionic compound, therefore it's melting and boiling points are higher than methyl chloride (CH₃Cl) which is a covalent compound. 

 

Question : Name the functional group present in each of the following organic compound:
(i) CH₃COCH₃ (ii) C₂H₅COOH
Answer : (i) CH₃COCH₃ —- >C=O ketonic group
(ii) C₂H₅COOH — (-COOH) Carboxylic acid

 

Question : Write the general formula for each of the following hydrocarbons and give one example for each.
(i) Alkene
(ii) Alkyne
Answer : (i) Alkene C_nH_2n e.g., C₂H₄ ethene
(ii) Alkyne C_nH_2n–2 e.g., C₂H₂ ethyne

Question : What is denatured alcohol?
Answer : When ethanol is mixed with methanol or some poisonous substances such as copper sulphate, pyridine which makes it unfit for drinking such alcohol is called denatured alcohol.

Question : Give two uses of ethanol and one harmful effect of it.
Answer :. Ethanol is a good solvent so it is used in making medicines such as tincture iodine, cough syrups and many tonics. Ethanol is also used in making alcoholic drinks.
Harmful effects: Intake of small amount of ethanol leads to drunkenness. Intake of even small amount of ethanol can be lethal. Long-term use or consumption can lead to severe health problems.

Question : (a) Name the compound CH₃COOH and identify its functional group.
(b) Give a chemical test to identify this compound.
(c) Name the gas evolved when this compound acts on solid sodium carbonate. How would you identify this gas? 
Answer : (a) Ethanoic acid, functional group is—COOH (Caboxylic/group)
(b) Take few drops of ethanoic acid in a test tube and add sodium hydrogen carbonate solution to it. Brisk effervescence of CO₂ gas is formed.
(c) CO₂ gas is evolved. To identify the gas, pass it through freshly prepared limewater, it turns milky due to the formation of milky white precipitate of CaCO₃.
Ca(OH)₂ + CO₂ ⎯⎯→ CaCO₃ + H₂O
                                    White ppt.

Question : Give reason for the following observations:
(a) The element carbon forms a very large number of compounds.
(b) Air holes of a gas burner have to be adjusted when the heated vessels get blackened by the flame.
(c) Use of synthetic detergents causes pollution of water. 
Answer : (a) Carbon forms large number of compounds due to its property of catenation, i.e. self linking. They form isomeric compounds i.e. compounds with same molecular formula but different structural formula.
(b) The vessels blacken due to deposits of black carbon particles on it which is caused due to incomplete combustion of fuel. Air holes are adjusted so that air enters through the holes and helps in complete combustion of the fuel.
(c) Synthetic detergent is non-biodegradable, it remains in the water thereby causing water pollution.

 

Question : (a) What is vinegar?
(b) Describe with a chemical equation, what happens when sodium hydrogen carbonate reacts with ethanoic acid. 
Answer : (a) The 5% – 10% aqueous solution of acetic acid is called vinegar.
(b) CH₃COOH + NaHCO₃ ⎯⎯→ CH₃COONa + H₂O + CO₂
    Acetic acid                             Sodium acetate
Ethanoic acid reacts with sodium bicarbonate to produce brisk effervescence of CO₂ gas and sodium acetate.

 

Long Answers

 

Question : Describe the addition reaction of carbon compounds with its application. State the function of catalyst in this reaction. How this reaction is different from a substitution reaction? Explain with an example. 

Answer : The addition reaction can be seen only with unsaturated carbon compounds. One example of addition reaction is hydrogenation reaction, which is used to obtain ghee from vegetable oil.

 

The rate of reaction increases in the presence of catalyst (Ni or Pt), they adsorb the hydrogen molecule over their surface thus increasing the rate of reaction.

In subsitution reaction, a reagent substitutes on atom or a group of atoms from the reactant instead of addition.

 

 

Question : List two reasons for carbon forming a large number of compounds. Name the type of Bonding found in most of its compounds. Why does carbon form compounds mainly by this kind of bonding?
Answer :  Carbon forms a large number of compounds.
The two properties of carbon which lead to the huge number of carbon compounds are:
-catenation: it’s a unique property of carbon atoms to form bonds with other atoms of Carbon giving rise to large molecules.
-Tetravalency: Since carbon has four valencies, it is capable of bonding with four other atoms Of carbon or atoms of some other monovalent elements.
Carbon compounds are formed mainly by sharing of electron with covalent bond because carbon atoms have 4 electrons in their outermost shell. So, needs to gain or lose Electrons to achieve inert gas electronic configuration. It could gain four electron forming C4-anion. But it is difficult due to energy consideration. It could lose 4 electrons to form C₄+cation. But it is difficult due to energy consideration.
Because of this reason carbon Share their electron to form covalent bond only.

 

 

Question : Define structural isomer and draw the isomeric structures of butane. Compare the structure of benzene and cyclohexane by drawing them. 

Answer :  Compounds having same molecular formula but different structural formula are called structural isomers.

e.g. butane (C₄H₁₀) shows the following two structural isomers. One of which is straight chain n-butane and other is iso-butane.

 

 

Question : The molecules involving ionic bond(s) are: 

Question : Which of the following compounds contain the functional group -OH? 
A. Propane
B. Propanol
C. Ethanoic acid
D. Ethanol
A) All of these
B) B and D
C) A and C
D) B and C
Answer : D
Explanation: Ethanol and propanol are alcohols and contain the functional group -OH. Ethanol is C₂H₅OH and propanol is C₃H₇OH. Ethanoic acid contains the carboxylic group (-COOH).

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

Short Answer Questions

i. Ethyl ethanoate ester is formed from ethanoic acid and ethanol.

ii. The process is called esterification.

Question : What happens when ethyl alcohol and acetic acid react with each other in presence of conc. H₂SO₄? Write the chemical equation. 

Answer : When ethyl alcohol reacts with acetic acid in presence of conc. H₂SO₄ a sweet smelling ester called ethyl acetate is formed as main product.

 

Another test: Unsaturated compounds decolourises bromine colour.

e.g.

 

But, saturated compounds does not decolourise the bromine water. Bayer's test can also be used to distinguish saturated and unsaturated hydrocarbon.

ii. Carbon dioxide and water are formed when ethane burns in air.

 

 

iii. The reactions in which a reagent substitutes (replace) atom or a group of atoms from the reactant (substrate) are called substitution reactions. These are generally shown by saturated compounds. When chlorine is added to hydrocarbons in the presence of sunlight, Cl replaces H-atoms one by one to give carbon tetrachloride as final product.

  

Question. Identify the following-
(i) An allotrope of carbon which has a two-dimensional layered structure consisting of flat hexagonal rings.
(ii) An allotrope of carbon which looks like a soccer ball.
(iii) An allotrope of carbon which contains both single and double bonds. 
Answer : (i) Graphite (ii) Buckminsterfullerene (iii) Graphite

Question. A hydrocarbon molecule contains 3 carbon atoms. What would be its molecular formula in case it is
(i) an alkane (ii) an alkene (iii) an alkyne? 
Answer : (i) General formula of alkanes = CnH_2n+2; if n=3, formula will be C₃H₈
(ii) General formula of alkanes = C_nH_2n; So, if n=3, formula will be C₃H₆
(iii) General formula of alkanes = C_nH_2n-2. So, if n=3, formula will be C₃H₄

Question. A hydrocarbon molecule has 4 carbon atoms. What would be its molecular formula in case it is
(i) an alkane (ii) an alkene (iii) an alkyne? 
Answer : (i) General formula of alkanes = C_nH_2n+2; if 2n+2 =10, n=4; so, formula will be C₄H₁₀
(ii) General formula of alkanes = CnH_2n; So, if 2n=8, n=4; so, formula will be C₄H₈
(iii) General formula of alkanes = CnH_2n-2. So, if 2n-2=6, n=4; so, formula will be C₄H₆

Long Answer Questions

Question. Define homologous series of organic compounds. List its two characteristics.Write the name and formula of the first member of the series of alkenes.
Answer : The series of organic compounds having same functional group and similar chemical properties is called homologous series. Each member differs from successive member by —CH₂— group. The difference in molecular weight between two successive members is 14 u. Characteristics: (i) It has same general formula, from which, all members can be derived. (ii) They have similar chemical properties. C₂H₄, CH₂=CH₂, Ethene is first member of alkene series.

Question. Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties. 
Answer : The series consists of members of same family with similar physical and chemical properties, therefore, called homologous series (i) CH₃OH, and (ii) CH₃CH₂OH are two consecutive members of homologous series. Alkyl group —CH₃ and —CH₃CH₂ part determines physical properties. Functional group —OH determines chemical properties of the compounds.

Question. (a) State two characteristic features of carbon which when put together give rise to a large number of carbon compounds.
(b) 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 : (a) The size of carbon atom is very small (Atomic radius = 77 pm) The strength C—C bond is quite high (355 kJ mol^-1) Therefore, any number of carbon atoms can be linked by covalent bonds, This self-linking property is called catenation. (b) Carbon shows catenation to large extent as compared to silicon as well as any other element due to smaller size of carbon. C—C bond is stronger than Si-Si bond because Si is larger in size, forms weaker bond.

Question. a) How can you prove that butene and propane are not in a given homologous  Series?
a) Name the first four homologues of alkene series?
b) How many covalent bonds are there in propene?
Answer : a) Propane has the formula C₃H₈ and butene is C₄H₈. C₃H₈ is of the form C_nH_2n+2 and belongs to alkane homologous series and C4H8 has the general formula C_nH_2n+2 which shows that it is an alkene. Hence those molecules are not in the same homologous series. Mention their chemical formula
b) Ethene(C₂H₄),Propene(C₃H₆), Butene(C4H8),Pentene(C₅H₁₀) 7 single covalent bond and one double bond

CASE STUDY BASED 

1. Read the following carefully.

In covalent compounds atoms share valence electrons to satisfy the octet. Each atom shares one pair or two pairs or three pairs of electrons depending on their combining capacity. In electron dot structures only number of valence electrons are shown around the symbols of constituent atoms. Carbon using its valency of four can make either single, double or triple bonds with other carbon atoms or any other atoms. Carbons self-linking property is called catenation. In hydrocarbons carbon makes aliphatic or cyclic molecules they are either saturated or unsaturated. Based on these facts Read the following paragraph and answer the questions given below.
An element X combines with Y to form a colourless odourless gas, Z which turns lime water milky is the major constituent of all organic molecules. Five X atoms combines with hydrogens to form a cyclic saturated hydrocarbon J and aliphatic unsaturated hydrocarbon Q.Q is used in gas welding.

Question.a) Identify compound Z and draw its electron dot structure.
Answer : a) Z is CO₂ its electron dot structure is

Question. Write the chemical formula and IUPAC name of compound Q
Answer : C₂H₂,ethyne

Question. What is the common name of Q
Answer : Acetylene

Question. How many single covalent bonds are present in compound J?
Answer : 15

Question. Draw the structure of J and write its chemical formula.
Answer : 

C₅H₁₀
Its chemical formula is C₅H₁₀

Value Based Questions

Question. Suman always carried her tiffin box in a jute bag while most of her friends got it packed in a poly bag.
(a) What type of bonding is present in polythene?
(b) Give one advantage of carrying jute and disadvantage of poly bag.
(c) Which value is reflected in Suman by using jute bag?
Answer : (a) In polythene, long chain of ethene is present – C = C –.
(b) Jute bag is biodegradable and will not cause pollution. While poly bag is nonbiodegradable and causes pollution.
(c) Suman shows the value of a responsible behaviour.