Write your observation when a piece of sodium is dropped in water.
When a piece of sodium is dropped in water then it reacts vigorously with water to form sodium hydroxide with the evolution of hydrogen gas in the form bubbles. This hydrogen gas catches fire and a large amount of heat releases. This is a highly exothermic reaction. The solution will be basic in nature because sodium hydroxide is formed.
2Na + 2H2O→2NaOH + H2