Question

Which of the following changes is/are a chemical change?

• A. Formation of curd from milk
• B. Dissolution of sugar in water
• C. Shredding a sheet of paper into bits
• D. Cooking of food

Answer 1

Answer: (A), (D)

The correct options are
A

Formation of curd from milk

D

Cooking of food

The enzymes secreted by the bacteria Lactobacillus convert milk into curd in which the chemical composition of milk is changed. Similarly, cooking is also a chemical change. The dissolution of sugar in water and shredding a piece of paper are examples of a physical change as no chemical reaction is involved in the processes.