Unit Test | Carbon And It's Compounds | Class 10 Science

MG SCHOOL SCIENCE

UNIT TEST – 04

CARBON AND ITS COMPOUNDS

Class 10 | Science | Chemistry

25 MARKS

Board Exam Preparation

Maximum Marks
25

Time Duration
50 Minutes

Total Questions
15

Student Name: ______________________________

Class & Section: ______________ Roll No: __________

Date: ______________________________

GENERAL INSTRUCTIONS

1. All questions are compulsory.
2. Read each question carefully.
3. Write balanced chemical equations wherever necessary.
4. Draw electron-dot structures wherever required.
5. Marks are indicated against each question.

SECTION A – MULTIPLE CHOICE QUESTIONS (5 × 1 = 5 Marks)

1. The valency of carbon is: 1 Mark

1 2 3 4

Correct answer: (D) 4. Carbon is tetravalent.

2. Which of the following is a saturated hydrocarbon? 1 Mark

Ethene Ethyne Ethane Propene

Correct answer: (C) Ethane. It contains only single covalent bonds.

3. Which functional group is present in ethanol? 1 Mark

–COOH –OH –CHO –CO–

Correct answer: (B) –OH, the hydroxyl group.

4. The molecular formula of ethanoic acid is: 1 Mark

CH₃OH C₂H₆ CH₃COOH C₂H₂

Correct answer: (C) CH₃COOH.

5. Which allotrope of carbon is the hardest naturally occurring substance? 1 Mark

Graphite Diamond Coal Charcoal

Correct answer: (B) Diamond.

SECTION B – ONE MARK QUESTIONS (4 × 1 = 4 Marks)

6. What is catenation? 1 Mark

The unique property of carbon atoms to form bonds with other carbon atoms, forming long chains, branched chains or rings, is called catenation.

7. Write the molecular formula of methane. 1 Mark

CH₄.

8. Name the functional group present in carboxylic acids. 1 Mark

Carboxyl group (–COOH).

9. What is the common name of ethanoic acid? 1 Mark

Acetic acid.

SECTION C – TWO MARK QUESTIONS (3 × 2 = 6 Marks)

10. Why does carbon form covalent bonds? Give two reasons. 2 Marks

1. Carbon has four electrons in its outermost shell.
2. It cannot easily lose or gain four electrons because of the large energy required. Therefore, it shares electrons to complete its octet and forms covalent bonds.

11. Differentiate between saturated and unsaturated hydrocarbons. Give one example of each. 2 Marks

Saturated hydrocarbons: Contain only single bonds between carbon atoms. Example: Ethane (C₂H₆).

Unsaturated hydrocarbons: Contain at least one double or triple bond between carbon atoms. Example: Ethene (C₂H₄).

12. What happens when ethanol reacts with sodium? Write the balanced chemical equation. 2 Marks

Ethanol reacts with sodium to produce sodium ethoxide and hydrogen gas.

2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑

SECTION D – THREE MARK QUESTIONS (2 × 3 = 6 Marks)

13. Explain the chemical properties of ethanol with suitable chemical equations. 3 Marks

(a) Reaction with sodium:
2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂

(b) Oxidation:
CH₃CH₂OH + 2[O] → CH₃COOH + H₂O
(Using an oxidising agent such as alkaline KMnO₄ or acidified K₂Cr₂O₇.)

(c) Dehydration:
C₂H₅OH → C₂H₄ + H₂O
(Concentrated H₂SO₄ at 443 K.)

14. Explain the cleansing action of soap with the help of micelle formation. 3 Marks

1. A soap molecule has a hydrophilic ionic head and a hydrophobic hydrocarbon tail.
2. The hydrophobic tails attach to oil and grease, while the hydrophilic heads remain in water.
3. Soap molecules form structures called micelles, trapping dirt and grease inside. The dirt is then washed away with water.

SECTION E – FOUR MARK QUESTION (1 × 4 = 4 Marks)

15. Answer the following questions about carbon compounds: 4 Marks

(a) What is a homologous series? (1 Mark)

(b) Write the molecular formula of the third member of the alkane series. (1 Mark)

(c) What is esterification? (1 Mark)

(d) Write the balanced chemical equation for the reaction between ethanoic acid and ethanol. (1 Mark)

(a) A homologous series is a family of organic compounds having the same functional group and general formula, with successive members differing by a –CH₂– unit.

(b) Propane – C₃H₈.

(c) The reaction between a carboxylic acid and an alcohol to form an ester and water is called esterification.

(d)

CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O

(Concentrated H₂SO₄ is used as a catalyst.)

YOUR TEST RESULT

0 / 5

Automatic evaluation covers five MCQs (5 marks). Descriptive answers require teacher evaluation (20 marks).

COMPLETE KEY ANSWERS – TEACHER'S REFERENCE

SECTION A – MCQ ANSWERS
1. D – 4
2. C – Ethane
3. B – Hydroxyl group
4. C – CH₃COOH
5. B – Diamond

SECTION B – ONE MARK ANSWERS

6. Catenation is the ability of carbon to form bonds with other carbon atoms.
7. CH₄.
8. Carboxyl group (–COOH).
9. Acetic acid.

SECTION C – TWO MARK ANSWERS

10. Carbon shares electrons to complete its octet because losing or gaining four electrons is energetically unfavourable.
11. Saturated compounds have only single carbon-carbon bonds; unsaturated compounds have double or triple carbon-carbon bonds.
12. Ethanol reacts with sodium to form sodium ethoxide and hydrogen gas: 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂.

SECTION D – THREE MARK ANSWERS

13. Reaction with sodium, oxidation and dehydration of ethanol. Refer to the balanced equations in Question 13.
14. Soap has hydrophilic heads and hydrophobic tails. It forms micelles around oily dirt, which is removed during washing.

SECTION E – FOUR MARK ANSWER

15. (a) Homologous series: A family of compounds with the same functional group and general formula.
    (b) Propane – C₃H₈.
    (c) Esterification is the formation of an ester from an alcohol and a carboxylic acid.
    (d) CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O.

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Class 10 Science – Carbon and Its Compounds