The diagram below shows the set up of the apparatus that would be used to prepare gas X.

Here are the answers to Question 8:

a) (i) Identify gas X.
Gas X is oxygen.

a) (ii) Describe the chemical identity test for gas X.
Insert a glowing splint into the gas. If oxygen is present, the splint will relight.

b) (i) What is the purpose of adding manganese (IV) oxide to hydrogen peroxide?
Manganese(IV) oxide ($\text{MnO}_2$) acts as a catalyst to speed up the decomposition of hydrogen peroxide.

b) (ii) Explain why this gas is obtained using the method shown in the diagram.
The method shown is collection over water. This method is used because oxygen gas is sparingly soluble in water.