MG SCHOOL SCIENCE
Unit Test Examination
Class 10 – Science
Chapter 2: Acids, Bases and Salts
Question Paper with Key Answers
Time: 1 Hour
Maximum Marks: 25
General Instructions:
- All questions are compulsory.
- Write answers neatly and clearly.
- Draw neat, labelled diagrams wherever necessary.
- Write balanced chemical equations wherever required.
- Marks are indicated against each question.
SECTION – A: MULTIPLE CHOICE QUESTIONS (5 × 1 = 5 Marks)
1 Mark
1. Which of the following represents a neutralisation reaction?
1 Mark
2. A compound that reacts with both acids and bases to produce salt and water is:
1 Mark
3. The gas liberated when sodium carbonate reacts with dilute hydrochloric acid is:
1 Mark
4. The compound used to remove permanent hardness of water is:
1 Mark
5. The molecular formula of lime water is:
SECTION – B: ONE-MARK QUESTIONS (4 × 1 = 4 Marks)
1 Mark
6. What is a neutralisation reaction?
1 Mark
7. What are alkalis?
1 Mark
8. Which ion is responsible for the acidic nature of an aqueous solution?
1 Mark
9. What is the chemical name of bleaching powder?
SECTION – C: TWO-MARK QUESTIONS (3 × 2 = 6 Marks)
2 Marks
10. Give scientific reason: While diluting an acid, the acid should be added to water and not water to acid.
2 Marks
11. The pH values of three solutions A, B and C are 5, 6 and 7 respectively.
(a) Which solution is the most acidic?
(b) Which solution is neutral?
(a) Which solution is the most acidic?
(b) Which solution is neutral?
2 Marks
12. Write any two chemical properties of acids.
SECTION – D: THREE-MARK QUESTIONS (2 × 3 = 6 Marks)
3 Marks
13. Draw the diagram of arrangement of the apparatus to show the reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning. Label the parts given below:
(i) Zinc granules
(ii) Soap solution
(ii) Soap solution
Reference: Arrangement of apparatus
Schematic reference diagram – redraw neatly in the answer sheet.
3 Marks
14. What is a strong acid? Explain how tooth decay is caused. How can it be prevented?
SECTION – E: FOUR-MARK QUESTION (1 × 4 = 4 Marks)
4 Marks
15. What is the chlor-alkali process? Name the three products obtained during this process and write one use of each product.
***** END OF QUESTION PAPER *****
ANSWER KEY AND MARKING SCHEME
Class 10 Science – Acids, Bases and Salts
SECTION A – MCQ ANSWERS (5 Marks)
1. (C) 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O
2. (A) Aluminium oxide.
3. (A) Carbon dioxide.
4. (A) Sodium carbonate.
5. (B) Ca(OH)₂.
SECTION B – ONE-MARK ANSWERS (4 Marks)
6. Neutralisation reaction:
The reaction between an acid and a base produces salt and water.
The reaction between an acid and a base produces salt and water.
7. Alkalis:
Bases that dissolve in water are called alkalis.
Bases that dissolve in water are called alkalis.
8. Acidic ion:
Hydrogen ion (H⁺) or hydronium ion (H₃O⁺).
Hydrogen ion (H⁺) or hydronium ion (H₃O⁺).
9. Chemical name of bleaching powder:
Calcium oxychloride (CaOCl₂).
Calcium oxychloride (CaOCl₂).
SECTION C – TWO-MARK ANSWERS (6 Marks)
10. Why should acid be added to water?
Dilution of concentrated acids is highly exothermic. If water is added to concentrated acid, the heat produced may cause the mixture to splash out and cause burns. Therefore, acid should be added slowly to water with continuous stirring.
Dilution of concentrated acids is highly exothermic. If water is added to concentrated acid, the heat produced may cause the mixture to splash out and cause burns. Therefore, acid should be added slowly to water with continuous stirring.
11. pH values:
(a) Solution A (pH 5) is the most acidic because it has the lowest pH value.
(b) Solution C (pH 7) is neutral.
(a) Solution A (pH 5) is the most acidic because it has the lowest pH value.
(b) Solution C (pH 7) is neutral.
12. Any two chemical properties of acids:
- Acids react with metals to produce salt and hydrogen gas.
- Acids react with bases to produce salt and water.
Zn + H₂SO₄ → ZnSO₄ + H₂
HCl + NaOH → NaCl + H₂O
SECTION D – THREE-MARK ANSWERS (6 Marks)
13. Zinc granules and dilute sulphuric acid experiment:
Labels:
Labels:
- Zinc granules
- Soap solution
Zn + H₂SO₄ → ZnSO₄ + H₂ ↑
Explanation:
- Zinc granules react with dilute sulphuric acid and produce zinc sulphate and hydrogen gas.
- The hydrogen gas is passed through soap solution, forming bubbles.
- When the hydrogen-filled bubbles are ignited, they burn with a characteristic pop sound.
14.
Acids that produce more H⁺ ions are called strong acids. After eating food, bacteria in the mouth decompose the remaining sugar and food particles, producing acids The best way to prevent this is to clean the mouth after eating
Acids that produce more H⁺ ions are called strong acids. After eating food, bacteria in the mouth decompose the remaining sugar and food particles, producing acids The best way to prevent this is to clean the mouth after eating
SECTION E – FOUR-MARK ANSWER (4 Marks)
15. Chlor-alkali process and its products:
The electrolysis of an aqueous solution of sodium chloride (brine) is called the chlor-alkali process.
Balanced chemical equation:
The electrolysis of an aqueous solution of sodium chloride (brine) is called the chlor-alkali process.
Balanced chemical equation:
2NaCl + 2H₂O → 2NaOH + H₂ + Cl₂
Three products and their uses:
- Sodium hydroxide (NaOH): Used in making soaps and detergents.
- Hydrogen (H₂): Used as a fuel and in the manufacture of ammonia.
- Chlorine (Cl₂): Used for disinfecting drinking water.
TOTAL: 25 / 25 MARKS
Excellent preparation! Keep learning Science.
