It's a combustion.

Combustions are part of what class of chemical reactions?

Combustions are oxidations

This reaction produces heat. It is an ... reaction.

exothermic

The white solid produced by combustion is sodium oxide. Write down its chemical formula!

Na₂O.

What is the meaning of the blue color of bromothymol?

It means that Na₂O reacts with water to form a base (hydroxide).

It's sodium hydoxide. Formula? Description?

NaOH. It is a white and water-soluble solid.

Write down the equations of the two observed reactions!

4Na+O₂→ 2Na₂O Na₂O+H₂O→ 2NaOH