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Agniveer Army CEE Carbon Compounds

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This page covers Agniveer Army CEE Carbon Compounds with complete concept notes, 12 graded practice MCQs, key points and exam-specific tips. Free to study.

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Concept Notes

Carbon Compounds— Rules & Concept

1.Core Concept

Read this first — the foundation of the topic

CARBON COMPOUNDS — CORE CONCEPT Carbon is a special element. It can form bonds with itself and with other elements to make millions of different compounds. This property is called covalent bonding. Carbon compounds are the basis of all living things and many everyday substances like petrol, plastics, and medicines.

Why is Carbon Special? Carbon has 4 electrons in its outer shell. It needs 4 more to complete its shell. So it shares electrons with other atoms. This sharing of electrons is called a covalent bond. Carbon can bond with carbon itself — this is called catenation. This gives carbon the ability to form long chains, branches, and rings.

2.Key Rules

Core rules you must know cold
Covalent Bonds

Carbon always forms 4 covalent bonds. Hydrogen forms 1. Oxygen forms 2. Nitrogen forms 3. 2

Homologous Series

A family of compounds with the same general formula and similar properties. Each member differs by CH2 (14 mass units). 3

Functional Groups

A group of atoms that gives a compound its characteristic properties. — OH (Hydroxyl) = Alcohols (e.g., Ethanol) — COOH (Carboxyl) = Carboxylic Acids (e.g., Acetic Acid) — CHO (Aldehyde) = Aldehydes — CO (Ketone) = Ketones 4

Saturated vs Unsaturated

— Saturated = only single bonds (Alkanes) — e.g., Methane (CH4) — Unsaturated = double or triple bonds (Alkenes, Alkynes) — e.g., Ethene (C2H4), Ethyne (C2H2)

3.Formula Block

Memorise — at least one formula appears in every paper

Alkanes: CnH(2n+2) — e.g., Methane CH4, Ethane C2H6

Alkenes: CnH(2n) — e.g., Ethene C2H4

Alkynes: CnH(2n-2) — e.g., Ethyne C2H2

4.Exam Patterns

What examiners ask — read before attempting PYQs
RRB Group D asks

identify functional groups, name of compounds, formula of a given compound, combustion reactions, and properties of ethanol vs ethanoic acid. Expect 1-2 questions from this topic. SHORTCUT / TRICK Trick 1 — Formula Memory: Mnemonic for Alkane formula CnH(2n+2) = "Carbon n, Hydrogen Double Plus Two". For Alkene = "Double n". For Alkyne = "Double Minus Two"

Trick 2 — Vinegar Trick

Ethanoic acid = acetic acid = vinegar. 3-4% solution = vinegar. If the question mentions sour taste or vinegar, the answer is ethanoic acid (CH3COOH).

5.Worked Example

Solve this step-by-step before moving on
1
Step 1

Alkane general formula = CnH(2n+2)

2
Step 2

4th member means n = 4

3
Step 3

Carbon atoms = 4

4
Step 4

Hydrogen atoms = (2×4) + 2 = 8 + 2 = 10

5
Step 5

Formula = C4H10 (Butane) Answer: C4H10

6.Exam Traps

Common mistakes students make — avoid these

Students confuse Ethanol (C2H5OH — alcohol, used in sanitisers) with Ethanoic Acid (CH3COOH — vinegar). Remember: Ethanol has OH group. Ethanoic acid has COOH group.

Both have 2 carbons but very different properties. Also, do NOT mix up alkene and alkyne formulas — alkyne has the minus 2 formula, not alkene.

Key Points to Remember

  • Carbon forms 4 covalent bonds — this is the reason it makes millions of compounds.
  • Catenation = carbon's ability to bond with itself to form chains, branches, and rings.
  • Alkane formula: CnH(2n+2) — saturated hydrocarbons with only single bonds.
  • Alkene formula: CnH(2n) — unsaturated, contain at least one double bond.
  • Alkyne formula: CnH(2n-2) — unsaturated, contain at least one triple bond.
  • Ethanol (C2H5OH) is an alcohol; Ethanoic Acid (CH3COOH) is acetic acid (vinegar).
  • Functional group -OH = Alcohol; -COOH = Carboxylic Acid; -CHO = Aldehyde.
  • Homologous series members differ by CH2 unit (molecular mass difference = 14).

Exam-Specific Tips

  • Methane (CH4) is the simplest carbon compound and the first member of the alkane series.
  • Ethanoic acid is commonly known as acetic acid; its 3-4% solution in water is called vinegar.
  • Ethanol formula is C2H5OH; it is used in alcoholic drinks, sanitisers, and as a fuel additive.
  • The process by which carbon bonds with carbon atoms is specifically called catenation.
  • Buckminster Fullerene (C60) is an allotrope of carbon shaped like a football (soccer ball).
  • Diamond and Graphite are both allotropes of carbon — Diamond is hardest, Graphite is a conductor.
  • Soap is made by the reaction of fat/oil with sodium hydroxide — this process is called saponification.
  • Biogas is mainly methane (CH4) — produced by decomposition of organic matter.
Practice MCQs

Carbon Compounds — Practice Questions

12graded MCQs · easy to hard · full solution & trap analysis

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Practice 1easy

Which of the following is the general formula for alkanes?

Practice 2easy

What is the molecular formula of ethene?

Practice 3easy

Which functional group is present in alcohols?

Practice 4easy

What type of bond exists between carbon atoms in diamond?

Practice 5medium

Which property of carbon allows it to form a vast number of organic compounds?

Practice 6medium

What is the general formula for saturated hydrocarbons (alkanes)?

Practice 7medium

Which of the following is a functional group present in alcohols?

Practice 8medium

What is the molecular formula of ethene (ethylene)?

Practice 9medium

Carboxylic acids contain which functional group?

Practice 10hard

Which of the following carbon compounds has a general formula CnH2n and contains one carbon-carbon double bond?

Practice 11hard

What is the IUPAC name of the compound with the structure CH3-CH2-CH2-CH3?

Practice 12hard

Which property of carbon allows it to form millions of different compounds?

60-Second Revision — Carbon Compounds

  • Remember: Carbon always makes 4 bonds — the foundation of all organic chemistry.
  • Formula: Alkane = CnH(2n+2), Alkene = CnH(2n), Alkyne = CnH(2n-2) — memorise this order.
  • Trick: Vinegar question = Ethanoic acid (CH3COOH); Sanitiser/alcohol question = Ethanol (C2H5OH).
  • Remember: Functional group -OH = Alcohol; -COOH = Acid — these are direct MCQ answers.
  • Trap: Do NOT confuse Ethanol with Ethanoic acid — both have 2 carbons but different functional groups.
  • Remember: Each next member in a homologous series adds CH2 (mass increases by 14).
  • Formula check: For 4th alkane — n=4, so C4H10 (Butane) — always substitute n in CnH(2n+2).
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