NCERT Question 3 - Chapter 6 Class 7 - Physical and Chemical Changes

Fill in the blanks in the following statements:

1. When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.
2. The chemical name of baking soda is _________.
3. Two methods by which rusting of iron can be prevented are _________ and _________.
4. Changes in which only _________ properties of a substance change are called physical changes.
5. Changes in which new substances are formed are called _________ changes.

Answer:

1. When carbon dioxide is passed through lime water, it turns milky due to the formation of calcium carbonate.
2. The chemical name of baking soda is sodium bicarbonate/ sodium hydrogen carbonate.
3. Two methods by which rusting of iron can be prevented are painting and galvanising.
4. Changes in which only physical properties of a substance change are called physical changes.
5. Changes in which new substances are formed are called chemical changes.