Question

Write a test to identify the gas evolved (if any) during the reaction of these metals with water.

When 2 mL of sodium hydroxide solution is added to few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as :

An aqueous solution turns phenolphthalein solution pink. When another aqueous solution is added to this pink solution, the pink colour disappears. Now when a few drops of the first solution are added to the reaction mixture, the mixture appears pink again. The respective changes in the nature of the solution are from :

Select a pair of natural indicator from the following :