A sample of soil is mixed with water and allowed to settle

• GC Acids Bases Salts

A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue?

1. Lemon juice
2. Vinegar
3. Common salt
4. An antacid

Answer

The pH paper gives greenish blue colour in weak alkaline medium so antacid (Mg(OH)₂) which is an alkaline compound will show greenish blue color on pH paper.

The correct option is D.