Based on the diagram, name the liquid in A and B and state the observation made in the combustion tube.

Here are the answers to your questions based on the provided diagram:

i) Name liquid:

• (I) A: Concentrated sulfuric acid ($\text{H}_2\text{SO}_4$)
• (II) B: Concentrated sulfuric acid ($\text{H}_2\text{SO}_4$) Explanation: Flasks A and B are placed after the oxygen removal step and are used to thoroughly dry the nitrogen gas by absorbing any remaining water vapor.

ii) Write down the observation made in the combustion tube.

• The hot copper turnings, which are reddish-brown, will turn black. *Explanation: Oxygen from the air reacts with the hot copper to form black copper(II)