EXPLANATION & SUMMARY

The chapter “Carbon and Its Compounds” from Class 10 Science is one of the most important and concept-rich chapters. It explores the world of organic chemistry—an entire branch of science devoted to carbon-based compounds. Carbon is a versatile and essential element that forms the basis of life on Earth, and its compounds are used in everything from fuels and plastics to medicines and textiles.

Introduction to Carbon

Carbon is a non-metal and the 6th element in the periodic table. It is placed in Group 14 and has 4 valence electrons. It is unique because it can form an incredibly large number of compounds — more than any other element.
Special Properties of Carbon:

Tetravalency – Carbon has four valence electrons, so it forms four covalent bonds with other atoms to achieve stability.
Catenation – Carbon has the ability to form long chains and rings by bonding with other carbon atoms. This self-linking property is called catenation.
Covalent Bonding – Carbon forms covalent bonds by sharing electrons (not by losing or gaining), which leads to the formation of stable and diverse compounds.

Types of Covalent Bonds
Depending on the number of electron pairs shared, covalent bonds can be:
Single bond – sharing of 1 pair of electrons (e.g., CH₄)
Double bond – sharing of 2 pairs of electrons (e.g., O₂)
Triple bond – sharing of 3 pairs of electrons (e.g., N₂)
In carbon compounds:
Ethane (C₂H₆) – single bonds
Ethene (C₂H₄) – one double bond
Ethyne (C₂H₂) – one triple bond

Versatile Nature of Carbon
Carbon’s versatility is due to:
Catenation – ability to form long chains and rings.
Tetravalency – forms 4 stable covalent bonds.
Formation of multiple bonds – single, double, or triple bonds.
Bonding with many elements – such as hydrogen, oxygen, nitrogen, sulfur, halogens, etc.

Saturated and Unsaturated Hydrocarbons

Hydrocarbons
These are compounds made of only carbon and hydrogen.
Saturated hydrocarbons (alkanes) – All bonds are single bonds.
General formula: CₙH₂ₙ₊₂
Example: Methane (CH₄), Ethane (C₂H₆)

Unsaturated hydrocarbons
Alkenes – contain one or more double bonds.
General formula: CₙH₂ₙ
Example: Ethene (C₂H₄)
Alkynes – contain one or more triple bonds.
General formula: CₙH₂ₙ₋₂
Example: Ethyne (C₂H₂)

Chains, Branches and Rings
Carbon atoms can form:
Straight chains – e.g., butane
Branched chains – e.g., isobutane
Rings – e.g., cyclohexane

Functional Groups

A functional group is an atom or group of atoms that imparts specific properties to a compound, regardless of the rest of the molecule.
Functional Group Symbol Example
Alcohol –OH CH₃OH (Methanol)
Aldehyde –CHO HCHO (Formaldehyde)
Ketone –CO– CH₃COCH₃ (Acetone)
Carboxylic acid –COOH CH₃COOH (Acetic acid)
Halogen –Cl, –Br, –I CH₃Cl (Chloromethane)

Homologous Series
A homologous series is a group of organic compounds having:
The same functional group.
Same general formula.
Successive members differ by –CH₂– unit.
Gradation in physical properties.
Similar chemical properties.
Example: Alkanes
CH₄, C₂H₆, C₃H₈, C₄H₁₀…

Nomenclature of Carbon Compounds
IUPAC (International Union of Pure and Applied Chemistry) naming includes:
Prefix – for substituent groups
Word root – number of carbon atoms (meth-, eth-, prop-, etc.)
Suffix – functional group (-ane, -ol, -al, -one, -oic acid)
Example: CH₃CH₂OH → Ethanol
Example: CH₃COOH → Ethanoic acid

Chemical Properties of Carbon Compounds
Combustion
Carbon compounds burn in oxygen to form CO₂ and H₂O with the release of heat and light.
CH₄ + 2O₂ → CO₂ + 2H₂O + Heat

Oxidation
Alcohols can be oxidized to acids using oxidizing agents like alkaline KMnO₄.
CH₃CH₂OH + [O] → CH₃COOH
Addition Reaction
In alkenes and alkynes, hydrogen is added in the presence of a catalyst like nickel.
C₂H₄ + H₂ → C₂H₆ (Ethene to Ethane)

Substitution Reaction
In saturated hydrocarbons, one or more hydrogen atoms are replaced by another atom or group.
CH₄ + Cl₂ → CH₃Cl + HCl (in the presence of sunlight)

Soap and Detergents
Soap
Soap is a sodium or potassium salt of long-chain carboxylic acids (fatty acids). It is formed by the saponification reaction:
Fat + NaOH → Soap + Glycerol
Soaps work effectively in soft water but form scum in hard water due to calcium or magnesium ions.

Detergents
Detergents are sodium salts of sulfonic acids. They are effective in both soft and hard water and are used in laundry powders and cleaning liquids.

Micelle Formation
When soap is added to water, the hydrophobic (water-repelling) tails of soap molecules surround the dirt/oil, while the hydrophilic (water-attracting) heads remain in water, forming spherical structures called micelles. This helps lift oily dirt off surfaces and wash it away.

Differences between Soap and Detergent
Soap Detergent
Made from natural fats and oils Made from petrochemicals
Less effective in hard water Works in hard and soft water
Biodegradable Some are non-biodegradable

Importance of Carbon Compounds
Carbon compounds form the backbone of:
Living organisms (proteins, carbohydrates, DNA)
Fuels (LPG, petrol, diesel)
Plastics, fibers, synthetic materials
Medicines and pharmaceuticals
Dyes, cosmetics, food preservatives

Conclusion

The chapter “Carbon and Its Compounds” reveals the incredible chemistry of carbon, which forms the structural and functional foundation of life and industry. Its ability to catenate, form covalent bonds, and bond with many different elements makes it extraordinarily versatile.
Understanding carbon’s compounds opens the door to organic chemistry—a vast and essential field of science with endless applications. This chapter builds a foundation for further studies in chemistry and encourages a deeper appreciation for the molecular world around us.

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QUESTIONS FROM TEXTBOOK

1. Ethane, with the molecular formula C₂H₆, has
(a) 6 covalent bonds
(b) 7 covalent bonds
(c) 8 covalent bonds
(d) 9 covalent bonds
Answer: (b) 7 covalent bonds
Ethane (C₂H₆) has a structure where two carbon atoms are bonded to each other by a single covalent bond, and each carbon atom is bonded to three hydrogen atoms [1]. This gives us:
1 carbon-carbon bond
6 carbon-hydrogen bonds
Total = 7 covalent bonds

2. Butanone is a four-carbon compound with the functional group
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol
Answer: (c) ketone
Butanone (C₄H₈O) is a four-carbon compound that contains a ketone functional group (-C=O) [1]. The ketone group is characterized by a carbonyl carbon atom bonded to two other carbon atoms, which distinguishes it from aldehydes where the carbonyl carbon is bonded to at least one hydrogen atom

3. 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) the fuel is not burning completely
When the bottom of a cooking vessel gets blackened, it indicates incomplete combustion of the fuel . This blackening is due to the deposition of unburnt carbon particles (soot) on the vessel surface . Complete combustion would produce a clean blue flame without soot formation, while incomplete combustion produces a yellow, sooty flame that deposits carbon particles .

4. Explain the nature of the covalent bond using the bond formation in CH₃Cl.
Answer:
The covalent bond in CH₃Cl (methyl chloride) demonstrates the sharing of electron pairs between atoms . Carbon has an atomic number of 6 with electronic configuration 2,4, meaning it has 4 valence electrons and requires 4 more electrons to complete its octet .
In CH₃Cl formation:
Carbon shares one electron each with three hydrogen atoms, forming three C-H single bonds
Carbon shares one electron with chlorine atom, forming one C-Cl single bond
Chlorine has 7 valence electrons and needs 1 more electron to complete its octet
Each atom achieves stable electronic configuration through electron sharing rather than electron transfer .
This covalent bonding explains why CH₃Cl has low melting and boiling points and is a poor conductor of electricity, as no ions are formed in the process .

5. Draw the electron dot structures for
(a) ethanoic acid (b) H₂S (c) propanone (d) F₂
Answer:
(a) Ethanoic acid (CH₃COOH):
The electron dot structure shows carbon forming four bonds – three with hydrogen atoms and one with the carboxyl group (-COOH) . The carboxyl group contains a carbon atom double-bonded to oxygen and single-bonded to a hydroxyl group (-OH) .
(b) H₂S (Hydrogen sulfide):
Sulfur has 6 valence electrons and shares 2 electrons with 2 hydrogen atoms, forming two S-H single bonds while retaining 2 lone pairs of electrons .
(c) Propanone (CH₃COCH₃):
The structure shows a three-carbon chain with the middle carbon double-bonded to oxygen (ketone group) and single-bonded to two methyl groups .
(d) F₂ (Fluorine molecule):
Each fluorine atom has 7 valence electrons and shares 1 electron with another fluorine atom, forming a single F-F bond while each atom retains 3 lone pairs

6. What is a homologous series? Explain with an example.
Answer:
A homologous series is a series of organic compounds that have the same functional group and similar chemical properties, but differ in their molecular formula by a constant unit of -CH₂- . Members of a homologous series show gradation in physical properties as molecular mass increases .
Example: Alkane series
Methane: CH₄
Ethane: C₂H₆
Propane: C₃H₈
Butane: C₄H₁₀
Characteristics of homologous series:
General formula: CₙH₂ₙ₊₂ for alkanes
Each successive member differs by -CH₂- unit (molecular mass difference of 14u)
Similar chemical properties due to same functional group
Gradual change in physical properties like melting point, boiling point, and solubility

7. How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
Answer:
Physical Properties:
Property
Ethanol
Ethanoic Acid
Odor
Pleasant, alcoholic smell
Pungent, vinegar-like smell
Taste
Burning taste
Sour taste
Melting Point
156 K
290 K
Boiling Point
351 K
391 K
Chemical Properties:
Litmus Test:
Ethanol: No effect on litmus paper
Ethanoic acid: Turns blue litmus paper red
Reaction with Sodium Carbonate:
Ethanol: No reaction with sodium carbonate
Ethanoic acid: Reacts with sodium carbonate to produce CO₂ gas that turns lime water milky
pH Value:
Ethanol: Nearly neutral (pH ≈ 7)
Ethanoic acid: Acidic (pH < 7)

8. 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:
Micelle formation occurs because soap molecules have a unique dual nature – they contain both hydrophilic (water-loving) and hydrophobic (water-repelling) parts . Soap molecules are sodium or potassium salts of long-chain carboxylic acids .
Structure of soap molecule:
Ionic head: Hydrophilic (attracts water)
Hydrocarbon tail: Hydrophobic (repels water, attracts oil/grease)
Micelle formation process:
When soap is added to water, the hydrophobic tails align away from water
The hydrophilic heads face towards water
This arrangement forms spherical structures called micelles
Oil droplets get trapped in the center of micelles, allowing them to be washed away
In ethanol:
Micelles will NOT form in ethanol because ethanol is a non-polar solvent . Soap molecules dissolve completely in ethanol without forming micelles, as the hydrophobic tails are soluble in the non-polar ethanol solvent .

9. Why are carbon and its compounds used as fuels for most applications?
Answer:
Carbon and its compounds are extensively used as fuels because they possess several advantageous properties
High Calorific Value:
Carbon compounds release large amounts of heat energy when burned
Complete combustion produces significant heat and light energy
Clean Combustion:
When burned in sufficient oxygen, they produce only CO₂ and H₂O
Products are relatively harmless compared to other fuel types
Easy Availability:
Carbon compounds like coal, petroleum, and natural gas are abundant
Renewable sources like ethanol can be produced from biomass
Efficient Energy Release:
The combustion reactions are highly exothermic
C + O₂ → CO₂ + heat and light
CH₄ + 2O₂ → CO₂ + 2H₂O + heat and light
Versatility:
Available in various forms (solid, liquid, gas)
Can be transported and stored easily

10. Explain the formation of scum when hard water is treated with soap.
Answer:
Scum formation occurs when soap reacts with hard water containing dissolved calcium and magnesium salts .
Chemical Reaction:
Soap (sodium stearate): 2C₁₇H₃₅COONa + Ca²⁺ → (C₁₇H₃₅COO)₂Ca + 2Na⁺
Soap (sodium stearate): 2C₁₇H₃₅COONa + Mg²⁺ → (C₁₇H₃₅COO)₂Mg + 2Na⁺
Process:
Hard water contains dissolved Ca²⁺ and Mg²⁺ ions
When soap is added, these ions react with soap molecules
Insoluble calcium and magnesium salts of fatty acids are formed
These insoluble salts appear as a grayish precipitate called scum
Consequences:
Reduces soap’s cleaning efficiency
Wastes soap as it gets consumed in scum formation
Scum deposits on clothes and bathtub surfaces
More soap is required for effective cleaning

11. What change will you observe if you test soap with litmus paper (red and blue)?
Answer:
When soap is tested with litmus paper, the following changes are observed :
Red Litmus Paper:
Red litmus paper turns blue when dipped in soap solution
This indicates that soap solution is basic/alkaline in nature
Blue Litmus Paper:
Blue litmus paper remains blue (no change)
This confirms the alkaline nature of soap solution
Explanation:
Soap is a sodium or potassium salt of long-chain fatty acids . When dissolved in water, soap undergoes hydrolysis to form alkaline solutions:
C₁₇H₃₅COONa + H₂O → C₁₇H₃₅COOH + NaOH
The formation of NaOH (sodium hydroxide) makes the solution alkaline, causing the characteristic litmus paper color changes

12. What is hydrogenation? What is its industrial application?
Answer:
Hydrogenation is a chemical process in which hydrogen gas is added to unsaturated organic compounds in the presence of a catalyst .
Process:
Unsaturated compounds (containing C=C or C≡C bonds) react with hydrogen
Catalysts used: Nickel, palladium, or platinum
Converts unsaturated compounds to saturated compounds
General reaction: C=C + H₂ → C-C (in presence of catalyst)
Industrial Applications:
Vegetable Oil Hydrogenation:
Converts liquid vegetable oils to solid fats (margarine, vanaspati)
Increases shelf life and stability of oils
Example: Sunflower oil → Solid cooking fat
Food Industry:
Production of solid fats from liquid oils
Manufacturing of margarine and shortening
Improves texture and consistency of food products
Pharmaceutical Industry:
Synthesis of various drugs and medications
Production of specific saturated compounds
Advantage: Hydrogenated oils have longer shelf life and better stability at room temperature compared to unsaturated oils

13. Which of the following hydrocarbons undergo addition reactions: C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄?
Answer:
Hydrocarbons that undergo addition reactions: C₃H₆ and C₂H₂
Explanation:
Addition reactions occur only in unsaturated hydrocarbons (compounds containing double or triple bonds)
Analysis of given compounds:
C₂H₆ (Ethane): Saturated hydrocarbon – No addition reaction
C₃H₈ (Propane): Saturated hydrocarbon – No addition reaction
C₃H₆ (Propene): Unsaturated hydrocarbon with C=C double bond – Undergoes addition reaction
C₂H₂ (Ethyne): Unsaturated hydrocarbon with C≡C triple bond – Undergoes addition reaction
CH₄ (Methane): Saturated hydrocarbon – No addition reaction
Examples of addition reactions:
C₃H₆ + H₂ → C₃H₈ (in presence of Ni catalyst)
C₂H₂ + H₂ → C₂H₄ (in presence of Ni catalyst)
Saturated hydrocarbons (alkanes) undergo substitution reactions instead of addition reactions .

14. Give a test that can be used to differentiate between saturated and unsaturated hydrocarbons.
Answer:
Bromine Water Test is used to differentiate between saturated and unsaturated hydrocarbons .
Procedure:
Take samples of both hydrocarbons in separate test tubes
Add bromine water (orange/red-brown solution) to each sample
Shake the test tubes gently
Observe the color changes
Results:
Unsaturated Hydrocarbons:
Bromine water decolorizes (loses its orange/red-brown color)
Becomes colorless or pale yellow
This indicates the presence of C=C or C≡C bonds
Saturated Hydrocarbons:
Bromine water retains its orange/red-brown color
No decolorization occurs
This confirms the presence of only single bonds
Chemical Explanation:
Unsaturated hydrocarbons undergo addition reactions with bromine
Example: C₂H₄ + Br₂ → C₂H₄Br₂
The bromine gets consumed in the reaction, causing decolorization
Saturated hydrocarbons do not react with bromine water under normal conditions

15. Explain the mechanism of the cleaning action of soaps.
Answer:
The cleaning action of soap is based on the formation of micelles and emulsification of dirt and grease
Structure of Soap Molecule:
Hydrophilic head: Ionic part (COO⁻Na⁺) – attracts water
Hydrophobic tail: Long hydrocarbon chain – attracts oil/grease
Mechanism of Cleaning:
Micelle Formation:
Soap molecules arrange themselves in spherical clusters
Hydrophobic tails point inward (away from water)
Hydrophilic heads point outward (towards water)
Dirt Entrapment:
Oil and grease particles get trapped in the center of micelles
Hydrophobic tails surround the dirt particles
Hydrophilic heads face the surrounding water
Emulsification:
Dirt particles become suspended in water as an emulsion
Micelles prevent dirt particles from reaggregating
Dirt particles can now be washed away with water
Removal:
Agitation (scrubbing/beating) helps break down larger dirt particles
Rinsing with water removes the emulsified dirt along with soap
Clean surface is left behind
Key Points:
Soap acts as an emulsifying agent
Reduces surface tension of water
Enables mixing of oil and water through micelle formation
Agitation is necessary for effective cleaning action
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OTHER IMPORTANT QUESTIONS FOR EXAMS

[CBSE MODEL QUESTION PAPER]

🔹 1. Multiple Choice Questions (10 × 1 = 10 Marks)
Q1. Which of the following statements correctly explains tetravalency of carbon?
(a) Carbon can lose four electrons
(b) Carbon can gain four electrons
(c) Carbon shares four electrons to form four covalent bonds
(d) Carbon forms ionic bonds only
Answer: (c)

Q2. Which of the following represents a saturated hydrocarbon?
(a) Ethene
(b) Ethyne
(c) Ethane
(d) Benzene
Answer: (c)

Q3. What is the general formula for alkanes?
(a) CₙH₂ₙ
(b) CₙH₂ₙ₊₂
(c) CₙH₂ₙ₋₂
(d) CₙH₂ₙO
Answer: (b)

Q4. The functional group –COOH belongs to:
(a) Alcohols
(b) Aldehydes
(c) Carboxylic acids
(d) Ketones
Answer: (c)

Q5. Which of the following is formed when ethanol is oxidized using alkaline KMnO₄?
(a) Methanoic acid
(b) Ethanoic acid
(c) Propanoic acid
(d) Ethene
Answer: (b)

Q6. Which of the following will decolourize bromine water?
(a) Ethane
(b) Ethene
(c) Methane
(d) Propane
Answer: (b)

Q7. Which is the correct IUPAC name for CH₃–CH₂–OH?
(a) Methanol
(b) Ethanol
(c) Ethanal
(d) Propanol
Answer: (b)

Q8. Micelle formation is possible because:
(a) Soaps are ionic in nature
(b) Soaps reduce water’s surface tension
(c) Soaps have hydrophobic and hydrophilic parts
(d) Soaps dissolve in oil
Answer: (c)

Q9. Which of the following is biodegradable?
(a) Detergent
(b) Plastic
(c) Soap
(d) PVC
Answer: (c)

Q10. Which of the following does not belong to the homologous series of alkanes?
(a) CH₄
(b) C₂H₆
(c) C₃H₈
(d) C₂H₄
Answer: (d)

🔹 2. Fill in the Blanks (3 × 1 = 3 Marks)

Q11. The ability of carbon to form bonds with other carbon atoms is called __.
Answer: Catenation

Q12. The IUPAC name of CH₃–COOH is __.
Answer: Ethanoic acid

Q13. A compound with general formula CₙH₂ₙ₋₂ belongs to the __ family.
Answer: Alkyne

🔹 3. Assertion and Reason Questions (3 × 1 = 3 Marks)

Choose: (A) Both A and R are true, R explains A; (B) Both A and R are true, R does not explain A; (C) A is true, R is false; (D) A is false, R is true.

Q14.
Assertion (A): Carbon can form long chains.
Reason (R): Carbon shows catenation.
Answer: A

Q15.
Assertion (A): Ethanoic acid reacts with sodium carbonate to release carbon dioxide.
Reason (R): Carboxylic acids are basic in nature.
Answer: C

Q16.
Assertion (A): Soap is effective in removing grease in soft water.
Reason (R): Soap molecules form micelles that trap oil and grease.
Answer: A

🔹 4. Right or Wrong? (2 × 1 = 2 Marks)
Q17. Detergents do not work in hard water.
Answer: Wrong – Detergents work effectively in both soft and hard water.

Q18. All hydrocarbons are organic but not all organic compounds are hydrocarbons.
Answer: Right

🔹 5. Short Answer Questions (5 × 3 = 15 Marks)
(Answer in about 50–70 words)

Q19. Why are carbon compounds generally poor conductors of electricity?
Answer: Carbon compounds are covalent in nature. They do not have free ions or electrons in their structure that can carry electric current. Hence, they do not conduct electricity under normal conditions.

Q20. How would you distinguish between ethanol and ethanoic acid using a chemical test?
Answer: Add sodium bicarbonate (NaHCO₃) to both. Ethanoic acid reacts with it to release CO₂ gas, seen as effervescence. Ethanol does not react this way. Thus, the effervescence confirms the presence of ethanoic acid.

Q21. What is a homologous series? Give two examples and state its characteristics.
Answer: A homologous series is a group of organic compounds with the same functional group and a difference of –CH₂– unit. Examples: Alkanes (CH₄, C₂H₆) and Alcohols (CH₃OH, C₂H₅OH). They show a gradual change in physical properties and have similar chemical behavior.

Q22. Explain the structure and working of a soap molecule in cleaning greasy dirt.
Answer: Soap molecules have two ends: hydrophilic (water-attracting) and hydrophobic (grease-attracting). When soap is added to greasy dirt, the hydrophobic tail sticks to grease and the hydrophilic head remains in water, forming micelles. These micelles trap grease and get rinsed away with water.

Q23. How is ethanol converted into ethanoic acid? Name the reagent and write the reaction.
Answer: Ethanol is oxidized to ethanoic acid using an oxidizing agent such as alkaline KMnO₄ or acidified K₂Cr₂O₇.
Reaction: CH₃CH₂OH + [O] → CH₃COOH

🔹 6. Long Answer Questions (2 × 5 = 10 Marks)
(Answer in about 120–150 words)

Q24. What is meant by isomerism? Explain with two examples.
Answer: Isomerism is a phenomenon where compounds have the same molecular formula but different structural arrangements of atoms. These compounds are called isomers.
Example 1: Butane (C₄H₁₀) –
n-butane: CH₃–CH₂–CH₂–CH₃
iso-butane: CH₃–CH(CH₃)–CH₃
Both have the same formula but different connectivity.
Example 2: Propanol (C₃H₈O) –
n-propanol: CH₃–CH₂–CH₂–OH
iso-propanol: CH₃–CHOH–CH₃This structural difference leads to different physical and chemical properties.

Q25. Explain the saponification reaction. What is micelle formation and why is soap not effective in hard water?
Answer: Saponification is the reaction of esters (from fats/oils) with sodium hydroxide to form soap and glycerol.
Reaction: Fat + NaOH → Soap + Glycerol
Micelle formation happens when soap molecules arrange themselves in water with their hydrophobic tails inwards and hydrophilic heads outwards. This traps grease in the center and cleans it. In hard water, soap reacts with calcium and magnesium ions to form insoluble scum, which reduces soap’s effectiveness.

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QUESTIONS FROM COMPETITIONS EXAMS

🔵 Question 1:
Which element forms the largest number of compounds?
(A) Hydrogen
(B) Carbon
(C) Nitrogen
(D) Oxygen
✅ Correct Answer: (B) Carbon
📄 Exam: SSC CGL 2020

🟢 Question 2:
Which of the following is an organic compound?
(A) Sodium chloride
(B) Calcium carbonate
(C) Ethanol
(D) Ammonium nitrate
✅ Correct Answer: (C) Ethanol
📄 Exam: IBPS Clerk 2018

🔴 Question 3:
Which type of bonding is found in organic compounds?
(A) Ionic
(B) Covalent
(C) Metallic
(D) Hydrogen
✅ Correct Answer: (B) Covalent
📄 Exam: RRB JE 2019

🟡 Question 4:
Which gas is evolved during the reaction of ethanoic acid and sodium bicarbonate?
(A) Hydrogen
(B) Nitrogen
(C) Carbon dioxide
(D) Oxygen
✅ Correct Answer: (C) Carbon dioxide
📄 Exam: SSC CHSL 2021

🔵 Question 5:
What is the chemical formula of methane?
(A) CH₄
(B) C₂H₆
(C) C₃H₈
(D) C₂H₄
✅ Correct Answer: (A) CH₄
📄 Exam: NDA 2017

🟢 Question 6:
Which of the following is used as fuel?
(A) Methane
(B) Ethanol
(C) Both A and B
(D) Sodium hydroxide
✅ Correct Answer: (C) Both A and B
📄 Exam: SSC MTS 2020

🔴 Question 7:
Which acid is present in vinegar?
(A) Formic acid
(B) Acetic acid
(C) Citric acid
(D) Hydrochloric acid
✅ Correct Answer: (B) Acetic acid
📄 Exam: CDS 2019

🟡 Question 8:
All organic compounds essentially contain:
(A) Nitrogen
(B) Hydrogen
(C) Carbon
(D) Oxygen
✅ Correct Answer: (C) Carbon
📄 Exam: SSC JE 2018

🔵 Question 9:
The functional group –OH is present in:
(A) Alcohols
(B) Aldehydes
(C) Ketones
(D) Carboxylic acids
✅ Correct Answer: (A) Alcohols
📄 Exam: RRB NTPC 2019

🟢 Question 10:
The compound used for making candles is:
(A) Methane
(B) Paraffin wax
(C) Acetone
(D) Benzene
✅ Correct Answer: (B) Paraffin wax
📄 Exam: SSC CPO 2020

🔴 Question 11:
Which of the following shows homologous series?
(A) CH₄, C₂H₆, C₃H₈
(B) HCl, HBr, HI
(C) H₂O, H₂S, H₂Se
(D) NaCl, KCl, LiCl
✅ Correct Answer: (A) CH₄, C₂H₆, C₃H₈
📄 Exam: SSC GD 2021

🟡 Question 12:
Which metal reacts with ethanol to produce hydrogen?
(A) Sodium
(B) Copper
(C) Iron
(D) Zinc
✅ Correct Answer: (A) Sodium
📄 Exam: NDA 2019

🔵 Question 13:
Which gas is produced on burning hydrocarbons?
(A) Nitrogen
(B) Oxygen
(C) Carbon dioxide
(D) Hydrogen
✅ Correct Answer: (C) Carbon dioxide
📄 Exam: IBPS PO 2016

🟢 Question 14:
Which is a saturated hydrocarbon?
(A) Ethane
(B) Ethene
(C) Ethyne
(D) Benzene
✅ Correct Answer: (A) Ethane
📄 Exam: SSC CGL 2019

🔴 Question 15:
What is the IUPAC name of CH₃COOH?
(A) Acetic acid
(B) Formic acid
(C) Propanoic acid
(D) Ethanoic acid
✅ Correct Answer: (D) Ethanoic acid
📄 Exam: SSC CHSL 2017

🟡 Question 16:
Which of the following does not conduct electricity?
(A) NaCl solution
(B) Alcohol
(C) HCl solution
(D) NaOH solution
✅ Correct Answer: (B) Alcohol
📄 Exam: SSC JE 2022

🔵 Question 17:
Which of these compounds is used in medicines as an antiseptic?
(A) Baking soda
(B) Iodine tincture
(C) Aspirin
(D) Carbolic acid
✅ Correct Answer: (D) Carbolic acid
📄 Exam: SSC GD 2020

🟢 Question 18:
Hardest form of carbon is:
(A) Coal
(B) Graphite
(C) Charcoal
(D) Diamond
✅ Correct Answer: (D) Diamond
📄 Exam: SSC CGL 2018

🔴 Question 19:
Which is the softest form of carbon?
(A) Graphite
(B) Diamond
(C) Coal
(D) Fullerene
✅ Correct Answer: (A) Graphite
📄 Exam: AFCAT 2019

🟡 Question 20:
Which of the following is used in dry cleaning?
(A) Acetone
(B) Petrol
(C) Benzene
(D) Carbon tetrachloride
✅ Correct Answer: (D) Carbon tetrachloride
📄 Exam: SSC JE 2021

🔵 Question 21:
What is the major constituent of LPG?
(A) Ethane
(B) Methane
(C) Propane and Butane
(D) Ethylene
✅ Correct Answer: (C) Propane and Butane
📄 Exam: CAPF 2020

🟢 Question 22:
Baking soda is chemically known as:
(A) Sodium carbonate
(B) Sodium bicarbonate
(C) Calcium bicarbonate
(D) Potassium carbonate
✅ Correct Answer: (B) Sodium bicarbonate
📄 Exam: SSC CGL 2021

🔴 Question 23:
Which carbon allotrope is used as a lubricant?
(A) Diamond
(B) Graphite
(C) Fullerene
(D) Charcoal
✅ Correct Answer: (B) Graphite
📄 Exam: SSC MTS 2019

🟡 Question 24:
The process of heating coal in absence of air is called:
(A) Calcination
(B) Roasting
(C) Distillation
(D) Destructive distillation
✅ Correct Answer: (D) Destructive distillation
📄 Exam: SSC CGL 2022

🔵 Question 25:
Which of the following is used as solvent in nail polish remover?
(A) Methanol
(B) Acetone
(C) Ethanol
(D) Benzene
✅ Correct Answer: (B) Acetone
📄 Exam: CDS 2020

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ONE PAGE REVISION SHEET

Carbon is a versatile element found in all living organisms and many materials we use daily. Its unique ability to form four covalent bonds (tetravalency) and catenation (forming long chains with itself) makes it special.

Covalent Bonding:
Carbon shares electrons to achieve noble gas configuration. Covalent compounds have low melting and boiling points, are poor conductors of electricity, and generally exist as gases, liquids, or soft solids.

Catenation and Tetravalency:
Due to catenation, carbon forms chains, branched chains, and rings. Tetravalency allows bonding with hydrogen, oxygen, nitrogen, halogens, etc.
Saturated and Unsaturated Compounds:
Saturated compounds (alkanes) have only single bonds (e.g., methane, ethane).
Unsaturated compounds include alkenes (double bond, e.g., ethene) and alkynes (triple bond, e.g., ethyne).

Homologous Series:
A group of organic compounds with the same functional group and a common difference of –CH₂. They show a gradation in physical properties and similar chemical properties.

Functional Groups:
Atoms or groups of atoms replacing hydrogen in hydrocarbons to change chemical properties.
Examples:
–OH (alcohol), –COOH (carboxylic acid), –CHO (aldehyde), –Cl (halo), –NH₂ (amine)

Nomenclature of Carbon Compounds:Based on root word (carbon atoms), suffix (bond type), and prefix (functional group). E.g., CH₃OH is methanol.

Important Reactions:
Combustion – Carbon compounds burn in air to release CO₂ and energy.
Oxidation – Alcohols to acids.
Addition reaction – Unsaturated hydrocarbons react with hydrogen.
Substitution reaction – Saturated hydrocarbons replace H with other atoms in the presence of sunlight.

Soaps and Detergents:
Soaps: Made from animal/vegetable fats + alkali, not effective in hard water.
Detergents: Made from petrochemicals, effective in hard water.
Important Carbon Compounds:
Ethanol and ethanoic acid – widely used in industries and homes.
Carbon’s bonding ability makes it the backbone of organic chemistry and life.

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ACRONYMS

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MISCONCEPTIONS “ALERTS”

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KNOWLEDGE WITH FUN

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MIND MAPS

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