CBSE Class 10 Science Carbon and its compounds Assignment Set 01

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.

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 :

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 – CH₂ – OH

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.

Answer : C

Question. CH3– CH2– OH Alkaline KMnO₄ + Heat > CH3 – COOH
In the above given reaction, alkaline KMnO4 acts as
(a) reducing agent
(b) oxidising agent
(c) catalyst
(d) dehydrating agent

Answer : B

Question. Carbon exists in the atmosphere in the form of
(a) carbon monoxide only
(b) carbon monoxide in traces and carbon dioxide
(c) carbon dioxide only
(d) coal

Answer : B

Question. In which of the following compounds, — OH is the functional group?
(a) Butanone
(b) Butanol
(c) Butanoic acid
(d) Butanal

Answer : B

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 : 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 

Question : Write the molecular formula and structural formula of acetaldehyde. 

Answer :   Molecular formula of acetaldehyde : CH₃CHO

Structural formula of acetaldehyde:

 

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 C_nH_2n+2
Alkenes are unsaturated hydrocarbons and are made up of compounds of carbon that are double bonded and has the general formula C_nH_2n.
Alkynes are also unsaturated hydrocarbons that are made up of compounds of carbon that are triple bonded and have a general formula C_nH_{2n – 2}
The structure of the first members of each series are as follows:

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.

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 + Na₂CO₃ → 2CH₃ COONa + CO₂+ H₂O 

 

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

 

e.g. CH₃COOH+NaOH →  CH₃ COONa+ H₂O

 

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.

Question : Reaction of water with aluminium carbide gives a colourles. gas. The gas is:
a. Methane
b. Acetylene
c. Ethane
d. Propane
Answer : A

 

Question : Diamond is not a good conductor of electricity because: 

a. It is not soluble in water.

b. It is very hard.

c. It has no free electrons to conduct electric current.

d. Its structure is very compact.
Answer : C

Explanation: Diamond is not a good conductor of electricity because it has no free electrons in its structure (like graphite) to conduct electric current.

 

Question : Substance ‘X’ is formed by the reaction of carboxylic acid and alcohol. It is used in making ice creams, cold drinks, perfumes and in flavoring agent. Name ‘X’. 

a. Aldehyde

b. Alkyne

c. Ester

d. Ketone

Answer : C

Explanation: Substance X is an ester. The reaction in which a carboxylic acid combines with an alcohol to form an ester is called esterification. Some volatile esters with characteristic odours are used in synthetic flavours, perfumes, and cosmetics. Certain volatile esters are used as solvents for lacquers, paints, and varnishes; large quantities of ethyl acetate and butyl acetate are commercially produced for this purpose.

 

 

Very Short Answers

 

Question : Would you be able to check if water is hard using a detergent? 

Answer : No, we can't check whether the water is hard or soft using a detergent. 

 

Question : What are constituents of an antifreeze? 

Answer : Ethylene glycol or ethanol is used as an antifreeze.

Question : Write the number of covalent bonds in the molecule of butane (C₄H₁₀).
Answer :  (i) Four, (ii) Four

Question : Which of the following is not observed in a homologous series? Give reason for your choice.
(a) Change in chemical properties (b) Difference in -CH₂ and 14u molecular mass
(c) Gradation in physical properties (d) Same functional group 
Answer : (a) It does not occur due to the presence of the same functional group.

Question : The general formula of three compounds A, B and C is C_nH₂n. ‘B’ has the highest boiling point and ‘C’ has the lowest boiling point.
(i) Mention the type of compounds A, B and C.
(ii) Which of these has minimum number of carbon atoms?
(iii) Name the homologous series to which A, B and C belong
Answer :  (i) Unsaturated hydrocarbons with double bonds.
(ii) ‘C’ has minimum boiling point, so ‘C’ has minimum no. of C-atoms.
(iii) Alkene

Question : An alkane has molecular weight 86. Write its molecular formula. What will be its physical state?
Answer : C₆H₁₄ has molecular weight of 6 × 12 + 14 = 86u.
It is in liquid state at room temperature

Question : The molecular formula of ‘A’ is C₁₀H₁₈ and ‘B’ is C₁₈H₃₆. Name the homologous series to which they belong. 
Answer : ‘A’ belongs to Alkynes, ‘B’ belongs to Alkenes.

Question : Write the next homologous of CH₃CH₂OH and HCOOH.
Answer : CH₃ – CH₂ – CH₂OH. Propanol and, CH₃COOH ethanoic acid

Question : Write the molecular formula of first two members of homologous series having functional group Cl.
Answer : The general formula of the compounds having – Cl functional group is C_nH_{2n + 1}Cl. Its two members are:
(i) CH₃Cl (ii) CH₃ – CH₂ – Cl

Question : Write the molecular formula of the 2nd and the 3rd member of the homologous series whose first member is methane (CH₄).
Answer :  (i) CH₃CH₃ (Ethane); where n is 2
(ii) CH₃CH₂CH₃ (Propane); where n is 3

Question : What is homologous series of carbon compounds? Give an example and list its three characteristics.
Answer : The series of organic compounds having same functional group and similar chemical properties is called homologous series. For example,
Alkane: CH₄ C₂H₆ C₃H₆
Methane Ethane Propane
Characteristics: • Each successive member differ by CH₂ unit.
• They have gradation in physical properties.
• They have similar chemical properties due to presence of same functional group

 

Short Answers

Question : Write the name and chemical formula of the simplest organic acid. 

Answer :  Formic acid is the simplest organic acid.

 

Question : Give names of the following: 

(a) An aldehyde derived from ethane

(b) Ketone derived from butane

(c) Compound obtained by the oxidation of ethanol by chromic anhydride

Answer :

 

 

Long Answers

 

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.

i. Identify the compound A.

ii. Write the chemical equation for its reaction with ethanol to form compound B.

iii. How can we get compound A form B?

iv. Name the process and write corresponding chemical equuation.

v. Which gas is produced when compound A reacts with washing soda? Write the chemical equation. 

Answer :

i. A is ethanoic acid (CH₃COOH). Commonly, known as acetic acid. Its 5 % solution in water is used to prepare vinegar, which is used as preservatives for pickles.

HOTS: (High Order Thinking Skill) Questions with Answers:

Question 1. An organic compound X with a molecular formula \(\text{C}_2\text{H}_6\text{O}\) undergoes oxidation with in presence of alkaline \(\text{KMnO}_4\) to form a compound Y. X on heating in presence of Conc. \(\text{H}_2\text{SO}_4\) at \(443\text{ K}\) gives Z, which on reaction with \(\text{H}_2\text{O}\) in presence of \(\text{H}_2\text{SO}_4\) gives back X. Z reacts with \(\text{Br}_2(\text{aq})\) and decolorizes it. Identify X, Y, & Z and write the reactions involved.
Answer: X is Ethanol (\(\text{CH}_3\text{CH}_2\text{OH}\)).
Y is Ethanoic acid (\(\text{CH}_3\text{COOH}\)).
Z is Ethene (\(\text{CH}_2=\text{CH}_2\)).
Reactions involved:
\(\text{CH}_3\text{CH}_2\text{OH} \xrightarrow{\text{Alkaline }\text{KMnO}_4\text{ + Heat}\\\text{Or acidified }\text{K}_2\text{Cr}_2\text{O}_7\text{ + Heat}} \text{CH}_3\text{COOH}\)
\(\text{CH}_3\text{CH}_2\text{OH} \xrightarrow[\text{H}_2\text{SO}_4]{\text{Hot conc.}} \text{CH}_2=\text{CH}_2 + \text{H}_2\text{O}\)
In simple words: Compound X is alcohol, Y is acid formed by oxidation, and Z is an unsaturated alkene formed by dehydration.

Exam Tip: Remember that alkaline \(\text{KMnO}_4\) or acidified \(\text{K}_2\text{Cr}_2\text{O}_7\) acts as an oxidizing agent to convert alcohols to carboxylic acids.

Question 2. An organic compound 'A' is widely used as a preservative in pickles and has a molecular formula \(\text{C}_2\text{H}_4\text{O}_2\). This compound reacts with ethanol to form a sweet smelling compound 'B'.
(i) Identify the compound 'A'
(ii) Write the chemical equation for its reaction with ethanol to form compound 'B'.
(iii) How can we get compound 'A' back from 'B'?
(iv) Name the process and write corresponding chemical equation.
(v) Which gas is produced when compound 'A' reacts with washing soda? Write the chemical equation.
Answer: (i) Compound 'A' is Ethanoic acid (\(\text{CH}_3\text{COOH}\)).
(ii) \(\text{CH}_3\text{COOH} + \text{CH}_3\text{CH}_2\text{OH} \xrightarrow{\text{Acid}} \text{CH}_3-\text{CO}-\text{O}-\text{CH}_2-\text{CH}_3 + \text{H}_2\text{O}\) (Ester)
(iii) Compound 'A' can be obtained back from 'B' by heating ester with an acid or a base.
(iv) The process is called Saponification.
Equation: \(\text{CH}_3\text{COOC}_2\text{H}_5 + \text{NaOH} \rightarrow \text{C}_2\text{H}_5\text{OH} + \text{CH}_3\text{COOH}\)
(v) Carbon dioxide (\(\text{CO}_2\)) gas is produced.
Equation: \(2\text{CH}_3\text{COOH} + \text{Na}_2\text{CO}_3 \rightarrow 2\text{CH}_3\text{COONa} + \text{H}_2\text{O} + \text{CO}_2\)
In simple words: Ethanoic acid reacts with alcohol to form sweet-smelling esters, which can be broken down using alkali.

Exam Tip: Always label the reactants and products clearly with their common or IUPAC names in esterification reactions.

Question 3. Hydrocarbon 'X' and 'Y' have molecular formulae \(\text{C}_3\text{H}_8\) and \(\text{C}_3\text{H}_6\) respectively. Both are burnt in different spatula on the bunsen flame. Indicate the color of the flame produced by 'X' and 'Y'. Identify 'X' and 'Y'. Write the structural formulae.
Answer: 'X' (\(\text{C}_3\text{H}_8\)) is a saturated hydrocarbon (propane) and burns with a clean blue flame.
'Y' (\(\text{C}_3\text{H}_6\)) is an unsaturated hydrocarbon (propene) and will burn with a sooty/yellowish flame due to incomplete combustion.
Structural formulae:
Propane (X): \(\text{CH}_3-\text{CH}_2-\text{CH}_3\)
Propene (Y): \(\text{CH}_3-\text{CH}=\text{CH}_2\)
In simple words: Saturated compounds burn with a clear blue flame, whereas unsaturated compounds give a smoky or sooty flame.

Exam Tip: Sooty flame is a characteristic feature of unsaturated hydrocarbons and aromatic compounds due to high carbon percentage.

Question 4. A compound 'X' has molecular formula \(\text{C}_4\text{H}_{10}\). It undergoes substitution reaction readily than addition reaction. It burns with blue flame and is present in LPG. Identify 'X' and give the balanced equation for its combustion and substitution reaction with \(\text{Cl}_2\) in presence of sunlight.
Answer: Compound 'X' is Butane (\(\text{C}_4\text{H}_{10}\)).
Combustion reaction:
\(2\text{C}_4\text{H}_{10} + 13\text{O}_2 \rightarrow 8\text{CO}_2 + 10\text{H}_2\text{O}\)
Substitution reaction:
\(\text{C}_4\text{H}_{10} + \text{Cl}_2 \xrightarrow{\text{Sunlight}} \text{C}_4\text{H}_9\text{Cl} + \text{HCl}\)
In simple words: Alkanes undergo substitution reactions because they are saturated hydrocarbons.

Question 5. 'A' compound works well with hard water. It is used for making shampoos & products for cleaning clothes. A is not 100% biodegradable and causes water pollution. 'B' does not work well with hard water. It is 100% biodegradable and does not create water pollution. Identify A & B.
Answer: 'A' is Detergent.
'B' is Soap.
In simple words: Detergents work in hard water but cause pollution, while soaps are biodegradable but form scum in hard water.

Exam Tip: Distinguish clearly between soaps (sodium/potassium salts of fatty acids) and detergents (ammonium/sulphonate salts).

Question 6. An organic compound P with molecular formula \(\text{C}_2\text{H}_6\text{O}\) is an active ingredient of all alcoholic drinks. It is also used in medicines such as tincture iodine, cough syrups. Identify 'P'. Drop a small piece of sodium into the test tube containing 'P'. A new compound 'Q' is formed with the evaluation of colorless and odorless gas Name the gas evolved and compound 'Q' write the chemical reaction.
Answer: 'P' is Ethanol (\(\text{CH}_3\text{CH}_2\text{OH}\)).
Gas evolved is Hydrogen (\(\text{H}_2\)).
Compound 'Q' is Sodium ethoxide (\(\text{CH}_3\text{CH}_2\text{O}^-\text{Na}^+\)).
Chemical reaction:
\(2\text{Na} + 2\text{CH}_3\text{CH}_2\text{OH} \rightarrow 2\text{CH}_3\text{CH}_2\text{O}^-\text{Na}^+ + \text{H}_2\)
In simple words: Reaction of active metals like sodium with alcohol releases hydrogen gas and forms alkoxide.

Exam Tip: This reaction is used as a test for the presence of alcoholic hydroxyl (\(-\text{OH}\)) groups.

Question 7. A cyclic compound 'X' has molecular formula \(\text{C}_6\text{H}_6\). It is unsaturated and burns with sooty flame. Identify 'X' and write its structural formula. Will it decolorize bromine water or not and why?
Answer: 'X' is Benzene (\(\text{C}_6\text{H}_6\)).
Structural formula is a ring of 6 carbon atoms with alternating single and double bonds, each bonded to one hydrogen atom.
It does not decolorize bromine water because it does not undergo addition reactions easily due to resonance stabilization.
In simple words: Benzene is unsaturated but behaves differently due to resonance, refusing to undergo normal alkene addition reactions.

Exam Tip: Draw the alternating double bond ring structure of benzene clearly when asked.

Question 8. An organic compounds 'A' is a constituent of antifreeze and has the molecular formula \(\text{C}_2\text{H}_6\text{O}\). upon reaction with alkaline \(\text{KMnO}_4\), the compound 'A' is oxidized to another 'B' with formula \(\text{C}_2\text{H}_4\text{O}_2\). Identify the compound A and 'B'. Write the chemical equation for the reaction which leads to the formulation of 'B'
Answer: Compound 'A' is Ethanol (\(\text{CH}_3\text{CH}_2\text{OH}\)).
Compound 'B' is Ethanoic acid (\(\text{CH}_3\text{COOH}\)).
Chemical equation:
\(\text{CH}_3-\text{CH}_2\text{OH} \xrightarrow{\text{Alkaline }\text{KMnO}_4\text{ + Heat}\\\text{Or acidified }\text{K}_2\text{Cr}_2\text{O}_7\text{ + Heat}} \text{CH}_3\text{COOH}\)
In simple words: Oxidation of ethanol yields ethanoic acid using oxidizing agents.

Exam Tip: Antifreeze alcohol is ethanol/ethylene glycol; here based on formula \(\text{C}_2\text{H}_6\text{O}\), it is ethanol.

Question 9. Two compounds 'X' and 'Y' have the same formula \(\text{C}_2\text{H}_4\text{O}_2\). One of them reacts with sodium metal to liberate \(\text{H}_2\) and \(\text{CO}_2\) with \(\text{NaHCO}_3\). Second one does not reacts with Na metal and \(\text{NaHCO}_3\) but undergo hydrolysis with \(\text{NaOH}\) to form salt of carboxylic acid and compound 'Z' which is called wood spirit. Identify 'X', 'Y', and 'Z' and write chemical equation for the reaction involved.
Answer: 'X' is Ethanoic acid (\(\text{CH}_3\text{COOH}\)).
'Y' is Methyl methanoate (\(\text{HCOOCH}_3\)).
'Z' is Methanol (\(\text{CH}_3\text{OH}\)).
Chemical equations:
\(\text{CH}_3\text{COOH} + \text{NaHCO}_3 \rightarrow \text{CH}_3\text{COONa} + \text{H}_2\text{O} + \text{CO}_2\)
\(\text{CH}_3\text{COOH} + \text{Na} \rightarrow \text{CH}_3\text{COONa} + \text{H}_2\)
\(\text{HCOOCH}_3 + \text{NaOH} \rightarrow \text{HCOONa} + \text{CH}_3\text{OH}\)
In simple words: Isomers having the same formula can be an acid and an ester; acids react with carbonates, esters undergo hydrolysis.

Exam Tip: Functional group isomers show entirely different chemical properties.

Question 10. A compound 'X' with molecular formula \(\text{C}_2\text{H}_4\) burns with a sooty flame. It decolorise bromine water. Identify 'X'. Will it dissolve in water or not? Will it conduct electricity in aq. Solution? Will it have high melting point or low melting point?
Answer: 'X' is Ethene (\(\text{C}_2\text{H}_4\)).
It will not dissolve in water (being covalent and non-polar).
It will not conduct electricity in aqueous solution (no ions are formed).
It has a low melting point (weak intermolecular forces).
In simple words: Ethene is a covalent unsaturated hydrocarbon, so it is insoluble in water, non-conducting, and low-melting.

Exam Tip: Carbon compounds are generally poor conductors of electricity and have low melting/boiling points.

PRACTICE QUESTIONS

Question 1. Write the formula for 'ethanoic acid' and name the functional group present in it.
Answer: Formula: \(\text{CH}_3\text{COOH}\).
Functional group: Carboxylic acid group (\(-\text{COOH}\)).
In simple words: Ethanoic acid contains a carboxyl functional group.

Exam Tip: Identify functional groups correctly from suffix names like '-oic acid'.

Question 2. Allotropy is a property shown by which class:- Substances, elements, compounds, mixture.
Answer: Elements.
In simple words: Allotropes are different physical forms of the same element.

Exam Tip: Diamond, graphite, and fullerenes are allotropes of carbon.

Question 3. What is the use of oxyacetylene flame?
Answer: Oxyacetylene flame is used for welding and cutting metals due to its extremely high temperature. Ethyne burns with oxygen to produce this high-temperature flame.
In simple words: It provides high heat used for welding metals together.

Exam Tip: Note that pure oxygen is used with ethyne, not air, to ensure complete combustion and high temperature.

Question 4. Name the gas which is formed by decomposition of plants and animal matter in marshy areas?
Answer: Methane (\(\text{CH}_4\)), also known as marsh gas.
In simple words: Methane is produced when organic matter decays in marshy places.

Question 5. Mention the name of the by product of soap industry/
Answer: Glycerol (Glycerin).
In simple words: Glycerol is left over as a useful byproduct when fats are saponified into soap.

Exam Tip: Glycerol is a trihydric alcohol produced during alkaline hydrolysis of fats/oils.

Question 6. Write the molecular formula and structures of benzene.
Answer: Molecular formula: \(\text{C}_6\text{H}_6\).
Structure: A hexagonal ring of six carbon atoms with alternate single and double bonds, each carbon attached to one hydrogen atom.
In simple words: Benzene has a ring structure with alternating double bonds.

Exam Tip: Practice drawing the hexagonal ring with alternating double bonds clearly.

Question 7. Match the following:-
1. Ethane - Used in anti freeze solution.
2. Ethanol - fruity smell.
3. Ester - fossil fuel.
Answer: 1. Ethane - fossil fuel.
2. Ethanol - Used in anti freeze solution.
3. Ester - fruity smell.
In simple words: Match each organic compound to its correct property or application.

Exam Tip: Double-check uses of common organic compounds before answering matching questions.

Question 8. Write two uses of fullerenes.
Answer: 1. Used as lubricants in miniature machinery.
2. Used in nanotechnology and medical applications for drug delivery.
In simple words: Fullerenes serve as lubricants and drug carriers.

Exam Tip: Fullerenes are spherical carbon allotropes, with \(\text{C}_{60}\) being the most famous.

Question 9. Complete and balance following equation:-
a) \(\text{CH}_2=\text{CH}_2 + \text{H}_2 \xrightarrow{\text{heat, Ni}}\)
b) \(\text{CH}_4 + \text{O}_2 \rightarrow\)
Answer: a) \(\text{CH}_2=\text{CH}_2 + \text{H}_2 \xrightarrow{\text{heat, Ni}} \text{CH}_3-\text{CH}_3\)
b) \(\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}\)
In simple words: Hydrogenation adds hydrogen across double bonds, and combustion produces carbon dioxide and water.

Exam Tip: Nickel or palladium acts as a catalyst in hydrogenation reactions.

Question 10. Two alkanes A and B have 4 and 6 carbon atoms respectively in their molecule. In which physical state will they occur at room temp?
Answer: Alkane A (Butane, \(\text{C}_4\text{H}_{10}\)) is a gas at room temperature.
Alkane B (Hexane, \(\text{C}_6\text{H}_{14}\)) is a liquid at room temperature.
In simple words: Lower alkanes are gases, while alkanes with higher molecular weights become liquids and solids.

Exam Tip: Alkanes from \(\text{C}_1\) to \(\text{C}_4\) are gases, \(\text{C}_5\) to \(\text{C}_{17}\) are liquids, and higher ones are solids.

Question 11. (1) Give a test that can be used to differentiate chemically between butter and cooking oil.
(2) How will you distinguish between ethanol and ethanoic acid by a suitable chemical test? Write chemical reactions involved.
(3) Complete the following reactions :-
1) \(\text{CH}_3\text{COOH} + \text{NaHCO}_3 \xrightarrow{\text{conc.H}_2\text{SO}_4}\)
2) \(\text{HCOOH} + \text{CH}_3\text{OH} \rightarrow\)
3) \(\text{CH}_3\text{COOC}_2\text{H}_5 + \text{H}_2\text{O} \rightarrow\)
(4) Name the compound \(\text{CH}_3\text{COOC}_2\text{H}_5\). Name the acid and alcohol from which it is made .write equation.
Answer: (1) Butter is saturated and does not decolorize bromine water, whereas cooking oil is unsaturated and decolorizes bromine water.
(2) Add sodium hydrogen carbonate (\(\text{NaHCO}_3\)) to both. Ethanoic acid will produce brisk effervescence of \(\text{CO}_2\) gas, while ethanol will not react.
Equation: \(\text{CH}_3\text{COOH} + \text{NaHCO}_3 \rightarrow \text{CH}_3\text{COONa} + \text{H}_2\text{O} + \text{CO}_2\)
(3)
1) \(\text{CH}_3\text{COOH} + \text{NaHCO}_3 \rightarrow \text{CH}_3\text{COONa} + \text{H}_2\text{O} + \text{CO}_2\)
2) \(\text{HCOOH} + \text{CH}_3\text{OH} \rightarrow \text{HCOOCH}_3 + \text{H}_2\text{O}\)
3) \(\text{CH}_3\text{COOC}_2\text{H}_5 + \text{H}_2\text{O} \xrightarrow{\text{Acid/Base}} \text{CH}_3\text{COOH} + \text{C}_2\text{H}_5\text{OH}\)
(4) Compound name: Ethyl ethanoate.
Acid: Ethanoic acid (\(\text{CH}_3\text{COOH}\)).
Alcohol: Ethanol (\(\text{C}_2\text{H}_5\text{OH}\)).
Equation: \(\text{CH}_3\text{COOH} + \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{Acid}} \text{CH}_3\text{COOC}_2\text{H}_5 + \text{H}_2\text{O}\)
In simple words: Use bromine water for unsaturation and bicarbonate test for acids.

Exam Tip: Bicarbonate test is specific for carboxylic acids among organic compounds in this syllabus.