Question

Separate the following into substances having pH values above and below 7. How do these influence litmus paper?
(i) Lemon juice (ii) Solution of washing soda (iii) Toothpaste (iv) Vinegar (v) Stomach juices

Answer 1

Substance	pH value	Litmus paper
Lemon juice	Below 7	Blue litmus turns red
Solution of washing soda	Above 7	Red litmus turns blue
Toothpaste	Above 7	Red litmus turns blue
Vinegar	Below 7	Blue litmus turns red
Stomach juices	Below 7	Blue litmus turns red

• Solutions having pH less than 7 are acidic in nature. They turn blue litmus to red.
  
• Substances having pH more than 7 are basic in nature (or alkaline in nature). They turn red litmus to blue.