Grade X: Acid, Base and Salt

Section A: Very Short Answer Questions (1 mark)

  1. What is an acid?
  2. What is a base?
  3. Define alkali.
  4. What are indicators?
  5. Name two natural indicators.
  6. What is the pH scale?
  7. What is the pH of a neutral solution?
  8. Which ion is responsible for acidic nature?
  9. Which ion is responsible for basic nature?
  10. Name one strong acid.
  11. Name one weak acid.
  12. Name one strong base.
  13. Name one weak base.
  14. What is universal indicator?
  15. What happens when acid reacts with a metal?
  16. Which gas is released when acid reacts with metal?
  17. What is neutralization reaction?
  18. Define salt.
  19. What is litmus?
  20. What is the colour of phenolphthalein in acid?
  21. What is the colour of methyl orange in base?
  22. What is water of crystallization?
  23. Give one example of hydrated salt.
  24. What is bleaching powder?
  25. What is baking soda?
  26. What is washing soda?
  27. What is plaster of Paris?
  28. Write the formula of hydrochloric acid.
  29. Write the formula of sodium hydroxide.
  30. What is the approximate pH of a strong acid?

Section B: Short Answer Questions (2–3 marks)

  1. Differentiate between acids and bases.
  2. Why do acids not show acidic nature in dry state?
  3. Why is dilution of acid exothermic?
  4. Why should acid be added to water slowly?
  5. Why does dry HCl gas not change blue litmus?
  6. Write the reaction of acid with metal.
  7. Write the reaction of acid with metal carbonate.
  8. What happens when acid reacts with bicarbonate?
  9. Define pH and state its importance.
  10. Why is pH important in digestion?
  11. Why are antacids used?
  12. Explain pH in tooth decay.
  13. Explain importance of soil pH.
  14. Define strong and weak acids with examples.
  15. Define strong and weak bases with examples.
  16. What are olfactory indicators? Give examples.
  17. What happens when base reacts with non-metal oxide?
  18. Why are bases called alkalies only in aqueous solutions?
  19. What happens when salts dissolve in water?
  20. What is hydrolysis of salt?
  21. How is common salt formed?
  22. State properties of acids.
  23. State properties of bases.
  24. Why does distilled water not conduct electricity?
  25. Why is water important in acid-base reactions?

Section C: Long Answer Questions (4–5 marks)

  1. Explain chemical properties of acids with equations.
  2. Explain chemical properties of bases with equations.
  3. Describe reactions of acids with metals, carbonates and oxides.
  4. Explain the pH scale in detail.
  5. Explain importance of pH in everyday life (any four points).
  6. Describe preparation and uses of bleaching powder.
  7. Describe preparation and uses of baking soda.
  8. Describe preparation and uses of washing soda.
  9. Explain formation and uses of plaster of Paris.
  10. Differentiate between strength and concentration of acids.
  11. What is water of crystallization? Explain with example.
  12. Why are acids, bases and salts electrolytes?
  13. Explain common salt and its products.
  14. Describe chlor-alkali process.
  15. Explain manufacturing of sodium hydroxide.

Section D: Assertion and Reason

  1. Assertion: Acids conduct electricity.
    Reason: They produce ions in aqueous solution.
  2. Assertion: Dry HCl gas is not acidic.
    Reason: It does not produce H⁺ ions.
  3. Assertion: pH of stomach is low.
    Reason: Hydrochloric acid is present in stomach.
  4. Assertion: Tooth decay occurs at low pH.
    Reason: Acid damages enamel.
  5. Assertion: Sodium carbonate is basic.
    Reason: It produces OH⁻ ions in water.

Section E: Case Study Questions

Case 1:

A student tested three solutions:
A → pH 2
B → pH 7
C → pH 10

Answer the following:

  1. Which solution is acidic?
  2. Which solution is basic?
  3. Which solution is neutral?
  4. Which has highest hydrogen ion concentration?
  5. Which is the strongest base?

Case 2:

A white powder is used in baking and releases carbon dioxide gas on heating.

Answer the following:

  1. Identify the compound.
  2. Write its chemical formula.
  3. Write the chemical equation.
  4. Why is CO₂ useful in baking?
  5. State two uses of this compound.

Section F: HOTS Questions

  1. Why do acids not show acidic behaviour without water?
  2. Why is mixing concentrated acid with water dangerous?
  3. Why does a bee sting cause irritation and how is it treated?
  4. Why is baking soda used in fire extinguishers?
  5. Why do farmers add lime to soil?
  6. Why is pH important for aquatic life?
  7. Why does curd taste sour?
  8. Why is sodium hydroxide stored in plastic containers?
  9. Why is toothpaste basic in nature?
  10. Why does acid rain damage buildings?

Section G: Numerical Questions

  1. Calculate pH if hydrogen ion concentration is 10⁻³ mol/L.
  2. Which is more acidic: pH 2 or pH 5?
  3. Arrange in increasing acidity: pH 3, 7, 9.
  4. What happens to acidity when pH increases?
  5. Identify strong and weak acids from given pH values.