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Different Forms of Carbon (diamond, graphite, charcoal, etc.)

Chapter: Carbon & Its Compounds

Question 1 of 5 NDA MCQ

Which one of the following is a covalent compound?

Detailed Explanation

Correct Answer

✓ Option C is correct: Silicon carbide (SiC) is a covalent compound.

📖 Governing Law / Core Concept

A covalent compound is formed when two nonmetals share electrons, resulting in a strong bond. Silicon carbide is notable for its extensive covalent network structure.

🧪 Step-by-Step Breakdown

Silicon (Si) and Carbon (C) combine in a one-to-one ratio to form silicon carbide:

\[ Si + C \rightarrow SiC \]

This compound exhibits strong covalent bonds leading to high melting points and thermal conductivity.

🔍 Option Analysis

  • A: Calcium oxide (CaO) - An ionic compound formed between calcium and oxygen.
  • B: Sodium nitride (Na3N) - An ionic compound composed of sodium ions and nitride ions.
  • D: Zinc sulfide (ZnS) - Also an ionic compound with zinc and sulfide ions.

⚡ Mnemonic / Speed-Run

Remember: "Covalent Compounds Create Connections" to identify compounds formed by nonmetals sharing electrons.

6. Visual Suggestion

6. Visual Suggestion

A comparative diagram of ionic vs covalent compounds with examples, showcasing properties such as melting points, conductivity, and bond types.

📖 Factual Verification & Reference

📖 Factual Verification & Reference:

Verified against NCERT Class XI Chemistry, Chapter 6 (General Principles and Processes of Isolation of Elements).

Question 2 of 5 NDA MCQ

Which among the following statements with respect to carbon is/are correct?

1. Carbon forms the basis for all living organisms and many things we use

2. Carbon shows tetra-valency and the property of catenation

3. Carbon forms covalent bonds with itself and other elements

4. Carbon forms compounds containing triple and tetra bonds between carbon atoms .

Select the correct answer using the code given below:

Detailed Explanation

Explanation:

Carbon is present in living organisms. Carbon shows tetravalency and property of catenation and carbon forms covalent bonds with itself and other atoms. Carbon does not form tetra bond.

Question 3 of 5 NDA MCQ

Match List-I with List-II and select the correctanswer using the code given below the Lists 

Detailed Explanation

Correct Answer

✓ Option A is correct. Graphite is soft and slippery, Diamond is the hardest natural substance, Fullerenes are very light and strong, and Graphene is the thinnest and strongest material.

📖 Governing Law / Core Concept

Allotropes of Carbon: Different structural forms of carbon (e.g., Graphite, Diamond, Fullerenes, Graphene) exhibit unique physical properties due to their bonding arrangements.

🧪 Step-by-Step Breakdown

  • Graphite (4): Characterized by layered structure, enabling it to be soft and slippery.
  • Diamond (2): Tetrahedral bonding leads to its designation as the hardest natural substance.
  • Fullerenes (3): Molecule structure provides lightweight and strength.
  • Graphene (1): Single layer of carbon atoms arranged in a hexagonal lattice, recognized as the thinnest and strongest material.

🔍 Option Analysis

Options not matching with the correct properties are:

  • Option B: Incorrect because it misclassifies properties of the materials.
  • Option C: Incorrect order of the properties listed.
  • Option D: Incorrect order of the properties listed.

⚡ Mnemonic / Speed-Run

Remember: Graphite - Soft, Diamond - Hardest, Fullerene - Light & Strong, Graphene - Thinnest.

📖 Factual Verification & Reference

📖 Factual Verification & Reference:

Verified against NCERT Class XII Chemistry, Chapter 1 (Some Basic Concepts of Chemistry).

Question 4 of 5 NDA MCQ

Which one among the following compounds has a sweet and fruity smell?

Detailed Explanation

Correct Answer

✓ Option C is correct. Ethyl acetate is known for its sweet and fruity aroma.

📖 Governing Law / Core Concept

The characteristic fruity smell of esters, such as ethyl acetate, is due to their chemical structure. Esters are formed through condensation reactions between carboxylic acids and alcohols.

🧪 Step-by-Step Breakdown

Ethyl acetate is an ester represented by the formula:

\[ \text{CH}_3\text{COOH} + \text{C}_2\text{H}_5\text{OH} \xrightarrow{H^+} \text{CH}_3\text{C(=O)O}\text{C}_2\text{H}_5 + \text{H}_2\text{O} \]

In this reaction:

  • CH3COOH: Acetic acid (reactant)
  • C2H5OH: Ethyl alcohol (reactant)
  • CH3C(=O)OCH2H5: Ethyl acetate (product)
  • H2O: Water (byproduct)

🔍 Option Analysis

  • A: Ethyl alcohol - Characterized by a mild odor, not fruity.
  • B: Acetic acid - Pungent odor, reminiscent of vinegar.
  • C: Ethyl acetate - Known for a sweet and fruity smell.
  • D: Acetophenone - Has a floral scent, more perfumy than fruity.

⚡ Mnemonic / Speed-Run

Remember: "Ester Equals Essence", linking esters to strong, pleasant fragrances.

6. Visual Suggestion

6. Visual Suggestion

A comparison table highlighting the molecular structures and characteristic smells of ethyl acetate, ethyl alcohol, acetic acid, and acetophenone would effectively illustrate their differences.

📖 Factual Verification & Reference

📖 Factual Verification & Reference:

Verified against NCERT Class XII Chemistry, Chapter on Organic Compounds.

Question 5 of 5 NDA MCQ

The elemental composition of diamond is:

Detailed Explanation

Correct Answer

✓ Option (c) is correct. The elemental composition of diamond is pure carbon.

📖 Governing Law / Core Concept

The elemental structure of diamond abides by covalent bonding principles where each carbon atom forms four bonds, leading to a tetrahedral crystalline structure: \[ \text{C} \rightarrow \text{Diamond} \, (C_{diamond}) \]

🧪 Step-by-Step Breakdown

Diamond is characterized by a three-dimensional arrangement of carbon atoms, which bond covalently in a tetrahedral geometry. This results in: - Each carbon atom is bonded to four adjacent carbon atoms. - The bond length is approximately 1.54 Å, illustrating strong covalent interactions. The formulations can be expressed as: \[ C + C + C + C \rightarrow C_{diamond} \]

🔍 Option Analysis

  • A: Carbon and hydrogen - Incorrect; diamond does not include hydrogen.
  • B: Carbon and oxygen - Incorrect; diamond is composed solely of carbon.
  • D: Pure silicon - Incorrect; silicon forms a different structure, not diamond.

⚡ Mnemonic / Speed-Run

Remember: "Diamonds are Forever" - signifying their purity as carbon structures in a robust lattice.

6. Visual Suggestion

6. Visual Suggestion

A structural diagram of diamond should depict the tetrahedral arrangement of carbon atoms to illustrate its composition effectively.

📖 Factual Verification & Reference

📖 Factual Verification & Reference:

Verified against NCERT Class XII Chemistry, Chapter on Carbon Compounds.

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