When sodium hydroxide solution is electrolysed :

When sodium chloride solution is electrolysed , the gas that is liberated at the cathode is ________.

When sodium chloride solution is electrolysed , the gas that is liberated at the cathode is ________.

What happens when sodium hydroxide solution is heated with zinc?

What do you observe when ? Sodium hydroxide solution is slowly added to zinc sulphate solution.

Explain the following: (i). Copper hydroxide is soluble in ammonium hydroxide but not in sodium hydroxide. (ii). A dark blue precipitate is formed when sodium hydroxide solution is added to copper sulphate solution. The precipitate darkens on heating.

Explain the following: (i). Copper hydroxide is soluble in ammonium hydroxide but not in sodium hydroxide. (ii). A dark blue precipitate is formed when sodium hydroxide solution is added to copper sulphate solution. The precipitate darkens on heating.