Which of the following statements about Acids and Bases are INCORRECT? I. Both acids and bases conduct electricity by producing i…

Question

Which of the following statements about Acids and Bases are INCORRECT?

I. Both acids and bases conduct electricity by producing ions in solution.

II. Antacids are weak bases that neutralise excess stomach acid.

III. Acidic solutions turn red litmus paper blue.

IV. Phenolphthalein is colourless in acid and pink in base.

V. Tooth decay starts at pH above 8.5.

1. A. II and IV only
2. B. III and V only (Correct answer)
3. C. I, II and IV only
4. D. II, III and V only

Correct Answer

Option B — III and V only

Detailed Solution & Explanation

The correct answer is III and V only.

Key Points

• INCORRECT statements: III — acids turn BLUE litmus RED (not red litmus blue).
• V — tooth decay starts at pH BELOW 5.5 (acidic), not above 8.5. Statements III and V are incorrect.