Name the type of chemical reactions involved in the cases given below:​

1. Burning of hydrogen to form water​

2. Passage of electricity through water that gives out hydrogen and oxygen ​

Q.

When hydrogen in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical changes involved in the two cases.

Q. When hydrogen burns in oxygen, water is formed. The type of chemical change involved is:

Q. In case of reaction between sodium and cold water, hydrogen burns with _______ flame, whereas, in case of reaction between potassium and cold water, hydrogen burns with _____ color.

Q.

Classify the following as chemical or physical changes:

• Cutting of trees

• Melting of butter in a pan

• Rusting of almirah

• Boiling of water to form steam

• Passing of electric current through water, and water breaking down into hydrogen and oxygen gas

• Dissolving common salt in water

• Making a fruit salad with raw fruits

• Burning of paper and wood