Daily Olympiad: Science - Acids Bases Salts [20260511] – 11 Practice Problems & Printable PDF

1. When an acid reacts with a metal carbonate, the gaseous product formed is:

A. Oxygen gas B. Hydrogen gas C. Carbon dioxide D. Nitrogen gas

Solution

Correct: C

Acids react with metal carbonates to produce carbon dioxide gas, along with a salt and water. For example: CaCO3 + 2HCl → CaCl2 + CO2 + H2O.

2. Which of the following is a strong base?

A. NH4OH B. Ca(OH)2 C. KOH D. Al(OH)3

Solution

Correct: C

KOH (Potassium hydroxide) is a strong base as it dissociates completely in water. NH4OH is weak, Ca(OH)2 is less soluble, and Al(OH)3 is amphoteric.

3. A solution with pH 7 turns the pH paper to:

A. Red B. Blue C. Green D. Yellow

Solution

Correct: C

pH 7 indicates a neutral solution. pH paper turns green in neutral conditions (pH 7), red in acids (<7), and blue/violet in bases (>7).

4. The chemical formula of caustic soda is:

A. Na2CO3 B. NaCl C. NaOH D. NaHCO3

Solution

Correct: C

Caustic soda is sodium hydroxide (NaOH), a strong base used in drain cleaners and soap manufacturing.

5. A salt formed from a strong acid and a weak base will have a pH:

A. Less than 7 B. Greater than 7 C. Equal to 7 D. Depends on the concentration

Solution

Correct: A

Salts from strong acids and weak bases (e.g., NH4Cl) hydrolyze in water to produce acidic solutions (pH <7) due to H+ ion generation.

6. Plaster of Paris is chemically:

A. CaSO4·2H2O B. CaSO4 C. CaSO4·½H2O D. CaCO3

Solution

Correct: C

Plaster of Paris (CaSO4·½H2O) hardens when mixed with water to form gypsum (CaSO4·2H2O), used in construction and orthopedics.

7. Which reaction is an example of neutralization?

A. HCl + NaOH → NaCl + H2O B. H2SO4 + Zn → ZnSO4 + H2 C. CaCO3 + 2HCl → CaCl2 + CO2 + H2O D. 2H2 + O2 → 2H2O

Solution

Correct: A

Neutralization reactions occur between acids and bases (H+ + OH− → H2O). Here, HCl (acid) and NaOH (base) form NaCl (salt) and water.

8. Phenolphthalein turns pink in:

A. Acids B. Bases C. Neutral solutions D. Both acids and bases

Solution

Correct: B

Phenolphthalein is a pH indicator that remains colorless in acids (pH <8.2) and turns pink in bases (pH >8.2).

9. A solution of which salt turns red litmus blue?

A. CaCl2 B. Al2(SO4)3 C. KNO3 D. Na2CO3

Solution

Correct: D

Sodium carbonate (Na2CO3) is a salt of a weak acid (H2CO3) and strong base (NaOH), making its aqueous solution alkaline (pH>7).

10. Metal oxides are generally:

A. Acidic B. Basic C. Neutral D. Amphoteric

Solution

Correct: B

Metal oxides react with acids to form salts and water, indicating basic properties (e.g., CaO + 2HCl → CaCl2 + H2O).

11. Baking soda is chemically:

A. Na2CO3 B. NaHCO3 C. NaOH D. NaCl

Solution

Correct: B

Sodium bicarbonate (NaHCO3) is used in baking as it releases CO2 when heated: 2NaHCO3 → Na2CO3 + CO2 + H2O.

Daily Olympiad: Science - Acids Bases Salts [20260511]

1. When an acid reacts with a metal carbonate, the gaseous product formed is:

2. Which of the following is a strong base?

3. A solution with pH 7 turns the pH paper to:

4. The chemical formula of caustic soda is:

5. A salt formed from a strong acid and a weak base will have a pH:

6. Plaster of Paris is chemically:

7. Which reaction is an example of neutralization?

8. Phenolphthalein turns pink in:

9. A solution of which salt turns red litmus blue?

10. Metal oxides are generally:

11. Baking soda is chemically:

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