Chapter 2: Acids, Bases and Salts — Online MCQ Test
SCIENCE · Grade 10 · CBSE(NCERT)
Practice Chapter 2: Acids, Bases and Salts with a free chapter-wise online MCQ test.
This chapter covers: chemistry-2.
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Chapter 2: Acids, Bases and Salts — Important Questions & Answers
What colour does red litmus paper turn in the presence of a base?
- A. Yellow
- B. Green
- C. Blue
- D. Remains red
Answer: C. Blue
Red litmus paper turns blue in the presence of a base, which is a key property used to identify basic solutions.
Red litmus paper turns blue in the presence of a base, which is a key property used to identify basic solutions.
Which gas is liberated when an acid reacts with a metal?
- A. Oxygen
- B. Carbon dioxide
- C. Nitrogen
- D. Hydrogen
Answer: D. Hydrogen
When an acid reacts with a metal, hydrogen gas is liberated along with a salt.
When an acid reacts with a metal, hydrogen gas is liberated along with a salt.
What is the common name of the compound CaOCl2?
- A. Washing soda
- B. Baking soda
- C. Bleaching powder
- D. Plaster of Paris
Answer: C. Bleaching powder
CaOCl2 is commonly known as bleaching powder.
CaOCl2 is commonly known as bleaching powder.
Which sodium compound is used for softening hard water?
- A. Sodium chloride
- B. Sodium hydrogen carbonate
- C. Sodium carbonate
- D. Sodium hydroxide
Answer: C. Sodium carbonate
Washing soda (Na2CO3·10H2O), which is sodium carbonate, is used for softening hard water.
Washing soda (Na2CO3·10H2O), which is sodium carbonate, is used for softening hard water.
A solution has a pH of 10. Which of the following best describes this solution?
- A. Strongly acidic
- B. Weakly acidic
- C. Neutral
- D. Basic
Answer: D. Basic
A pH of 10 is greater than 7, which indicates a basic solution. It also turns red litmus paper blue.
A pH of 10 is greater than 7, which indicates a basic solution. It also turns red litmus paper blue.
When a solution of an acid is diluted, what happens to the concentration of hydronium ions?
- A. It increases
- B. It remains the same
- C. It decreases
- D. It first increases then decreases
Answer: C. It decreases
Dilution adds water, which decreases the number of hydronium ions per unit volume, reducing the acid's strength.
Dilution adds water, which decreases the number of hydronium ions per unit volume, reducing the acid's strength.
Arrange the following pH values in increasing order of hydrogen ion concentration: 11, 9, 7, 4, 1.
- A. 1 < 4 < 7 < 9 < 11
- B. 11 < 9 < 7 < 4 < 1
- C. 7 < 4 < 1 < 9 < 11
- D. 4 < 1 < 7 < 9 < 11
Answer: B. 11 < 9 < 7 < 4 < 1
pH is inversely related to hydrogen ion concentration. As pH decreases, H+ concentration increases. So order of increasing H+ concentration is pH 11 < 9 < 7 < 4 < 1.
pH is inversely related to hydrogen ion concentration. As pH decreases, H+ concentration increases. So order of increasing H+ concentration is pH 11 < 9 < 7 < 4 < 1.
Which statement about the strength of acids and bases is correct?
- A. Weak acids are dilute and strong acids are concentrated
- B. Strength depends on degree of ionization, not concentration
- C. All concentrated acids are strong acids
- D. A weak acid in concentrated form becomes a strong acid
Answer: B. Strength depends on degree of ionization, not concentration
Acid strength is determined by degree of ionization (percentage of molecules that ionize), independent of concentration. A dilute strong acid is still strong.
Acid strength is determined by degree of ionization (percentage of molecules that ionize), independent of concentration. A dilute strong acid is still strong.
Which of the following best explains why concentrated sulfuric acid is a strong dehydrating agent while dilute sulfuric acid is not?
- A. Concentration determines acid strength, not dehydrating ability
- B. Concentrated H2SO4 has high affinity for water and removes it from substances, while dilute form is diluted with water
- C. Dilute H2SO4 is a weak acid and cannot remove water
- D. Only concentrated acids show exothermic reactions with water
Answer: B. Concentrated H2SO4 has high affinity for water and removes it from substances, while dilute form is diluted with water
Concentrated H2SO4 absorbs water strongly due to high affinity; addition to water is highly exothermic. Dilute H2SO4 already contains water, so it cannot dehydrate.
Concentrated H2SO4 absorbs water strongly due to high affinity; addition to water is highly exothermic. Dilute H2SO4 already contains water, so it cannot dehydrate.
A student prepares a buffer solution. After measuring its pH as 4.8, they add 10 mL of 0.1 M HCl to 100 mL of buffer. The pH is expected to:
- A. Drop to approximately 1.8
- B. Drop slightly to around 4.6-4.7
- C. Remain unchanged at 4.8
- D. Increase to 5.2
Answer: B. Drop slightly to around 4.6-4.7
A buffer resists pH change. Adding small amount of strong acid causes slight pH decrease (to ~4.6-4.7) as buffer's basic component neutralizes added H+ ions.
A buffer resists pH change. Adding small amount of strong acid causes slight pH decrease (to ~4.6-4.7) as buffer's basic component neutralizes added H+ ions.