Step 1: Identify process A. Process A shows a change from Gas to Solid. This process is called deposition or desublimation. 25. (i) A: $\boxed{\text{Deposition}}$ Step 2: Identify process C. Process C shows a change from Gas to Liquid. This process is called condensation. 25. (i) C: $\boxed{\text{Condensation}}$ Step 3: Identify the process for Naphthalene and Iodine. Naphthalene and Iodine are substances that change directly from solid to gas without passing through a liquid state. This process is called sublimation. 25. (ii) Process: $\boxed{\text{Sublimation}}$ Step 4: Identify Y in the oxygen preparation setup. The diagram shows sodium peroxide reacting to produce oxygen gas, which is collected over water. Liquid Y is added to the sodium peroxide to initiate the reaction. Sodium peroxide reacts with water to produce oxygen. Therefore, Y is water. 26. (a) Y: $\boxed{\text{Water}}$ Step 5: State a precaution for the experiment. The reaction between sodium peroxide and water is highly exothermic and can be vigorous, producing a lot of heat and gas quickly. To control the reaction and prevent it from becoming too violent or overflowing, the water should be added slowly. 26. (c) Precaution: Add water slowly to control the rate of reaction and prevent overheating or frothing. 3 done, 2 left today. You're making progress.