⚗️ Acids, Bases and Salts – Class 10 Science MCQs

Part 4: HOTS, Applications, Numericals & Real-Life Questions (Q76–Q100)

Q76. Which statement is correct about strong acids?

A. They always have low pH
B. They completely ionize in water
C. They are always dangerous to touch
D. They cannot be neutralized

✅ Correct Answer: B. They completely ionize in water

Explanation: Strength of acid depends on ionization, not just pH or corrosiveness.

Q77. Which of the following will have pH > 7?

A. Lemon juice
B. Milk
C. NaOH solution
D. Vinegar

✅ Correct Answer: C. NaOH solution

Q78. Which solution will turn phenolphthalein pink?

A. NaOH
B. HCl
C. H₂SO₄
D. CH₃COOH

✅ Correct Answer: A. NaOH

Q79. Which of the following is used to detect end point in acid–base titration?

A. Water
B. Phenolphthalein
C. NaCl
D. Baking soda

✅ Correct Answer: B. Phenolphthalein

Q80. Which acid is produced in the stomach and causes indigestion if excess is secreted?

A. H₂SO₄
B. HNO₃
C. HCl
D. CH₃COOH

✅ Correct Answer: C. HCl

Q81. Which compound is used to neutralize acidic soil?

A. NaCl
B. Ca(OH)₂
C. HCl
D. Na₂CO₃

✅ Correct Answer: B. Ca(OH)₂ (slaked lime)

Q82. Which acid is produced when SO₂ dissolves in water?

A. HCl
B. HNO₃
C. H₂SO₃
D. H₂SO₄

✅ Correct Answer: C. H₂SO₃ (Sulphurous acid)

Q83. Which of the following is a basic salt?

A. NaCl
B. Na₂CO₃
C. NH₄Cl
D. KNO₃

✅ Correct Answer: B. Na₂CO₃

Explanation: Carbonate ions hydrolyze → gives basic nature.

Q84. The pH of a solution is 3. It is:

A. Strongly acidic
B. Weakly acidic
C. Neutral
D. Basic

✅ Correct Answer: A. Strongly acidic

Q85. The pH of a solution is 11. It is:

A. Strongly acidic
B. Weakly acidic
C. Strongly basic
D. Neutral

✅ Correct Answer: C. Strongly basic

Q86. Which of these salts gives acidic solution?

A. NaCl
B. KCl
C. NH₄Cl
D. Na₂CO₃

✅ Correct Answer: C. NH₄Cl

Explanation: Strong acid (HCl) + weak base (NH₄OH) → acidic salt.

Q87. A student adds water to concentrated H₂SO₄ directly. What will happen?

A. Dilution takes place safely
B. Nothing happens
C. Mixture may splash and cause burns
D. Water evaporates immediately

✅ Correct Answer: C. Mixture may splash and cause burns

Explanation: Always add acid to water, never the reverse.

Q88. Which process is used to obtain NaCl from sea water?

A. Filtration
B. Distillation
C. Evaporation
D. Crystallization

✅ Correct Answer: C. Evaporation

Q89. Which chemical is used for making soda-acid fire extinguishers?

A. NaCl
B. Na₂CO₃
C. NaHCO₃
D. CaSO₄

✅ Correct Answer: C. NaHCO₃ (baking soda)

Q90. The pH of rainwater collected in a city was found to be 4. What can be concluded?

A. It is pure
B. It is acidic due to acid rain
C. It is basic
D. It is neutral

✅ Correct Answer: B. It is acidic due to acid rain

Q91. Which property of acids is responsible for corrosion of metals?

A. They are sweet in taste
B. They liberate hydrogen gas on reaction with metals
C. They release CO₂ with carbonates
D. They dissolve in organic solvents

✅ Correct Answer: B. They liberate hydrogen gas on reaction with metals

Q92. The plaster of Paris is prepared by heating:

A. CaSO₄·2H₂O to 100°C
B. CaSO₄·2H₂O to 170°C
C. CaCO₃ at high temperature
D. CaO with water

✅ Correct Answer: B. CaSO₄·2H₂O to 170°C

Q93. A solution turns red litmus blue. Its pH is likely to be:

A. 5
B. 7
C. 9
D. 3

✅ Correct Answer: C. 9

Q94. Which chemical is used to manufacture bleaching powder?

A. NaOH
B. Cl₂
C. Ca(OH)₂
D. Both B and C

✅ Correct Answer: D. Both B and C

Explanation: Ca(OH)₂ + Cl₂ → CaOCl₂.

Q95. Washing soda recrystallizes to form:

A. Na₂CO₃·5H₂O
B. Na₂CO₃·10H₂O
C. Na₂CO₃·2H₂O
D. Na₂CO₃·7H₂O

✅ Correct Answer: B. Na₂CO₃·10H₂O

Q96. The compound used to neutralize the acidity of soil is:

A. NaCl
B. Ca(OH)₂
C. HCl
D. NH₄Cl

✅ Correct Answer: B. Ca(OH)₂ (slaked lime)

Q97. Which chemical is used in the preparation of glass and paper?

A. Baking soda
B. Washing soda
C. POP
D. Bleaching powder

✅ Correct Answer: B. Washing soda

Q98. Which salt is used in making toys, idols, and bandages?

A. Baking soda
B. Washing soda
C. POP
D. NaCl

✅ Correct Answer: C. POP (Plaster of Paris)

Q99. Which of the following has detergent properties?

A. NaOH
B. NaCl
C. Na₂CO₃
D. NaHCO₃

✅ Correct Answer: C. Na₂CO₃ (washing soda)

Q100. Which statement about pH is correct?

A. Higher pH means higher acidity
B. Lower pH means higher acidity
C. pH has no relation to acidity or alkalinity
D. Neutral solution always has pH = 0

✅ Correct Answer: B. Lower pH means higher acidity

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