Why this heated in a heating tube and why a tube containing calcium oxide is used?

In a heating tube, materials are heated to induce chemical reactions or phase changes. Calcium oxide (CaO) is often used in these tubes because it has a high melting point and can absorb moisture, making it effective for creating a dry environment. Additionally, CaO acts as a dehydrating agent and can help in the removal of water from reactions, enhancing the efficiency of various processes.