pH and Indicators — Prelims Questions

Which of the following statements about pH and indicators is INCORRECT?

Consider the following statements regarding soil pH and its agricultural implications: 1. Acidic soils can be neutralized by adding quicklime or slaked lime. 2. Highly alkaline soils can be treated by adding organic matter or gypsum. 3. Most crops thrive optimally in a soil pH range of 4.5 to 5.5. Which of the statements given above is/are correct?

A solution turns red litmus blue and gives a pink color with phenolphthalein. What can be inferred about the solution's pH?

Which of the following is NOT a natural pH indicator?

Ocean acidification is a significant environmental concern. Which of the following best describes the primary cause and effect related to pH?