A solution turns red litmus blue. Which of the following is the most likely pH of this solution?
(a) 2
(b) 5
(c) 7
(d) 10
Generated by claude-sonnet-4-6 · 2026-06-15 06:41 · grounding rag
Model Answer
(d) 10
A solution that turns red litmus blue is basic (alkaline) in nature. Basic solutions have pH greater than 7. Among the given options, 10 is the only value above 7, making it the correct answer.
Source: Chapter 2, Section 2.1.1 & Exercises Q.1
Explanation
- Red litmus turns blue only in a basic/alkaline solution.
- Acidic solutions (pH < 7) keep red litmus red; neutral solutions (pH = 7) cause no change.
- pH > 7 = basic. Among options, only 10 is greater than 7.
- Note: The textbook exercise has the same question with option (d) 10 as the answer — examiners expect you to recall that alkaline solutions have pH > 7.