Which gas is used in the process of converting vegetable oils into vegetable ghee?

An element $A$ is soft and can be cut with a knife. It is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following:

Which process is used to convert vegetable oil into vegetable ghee?

What is the atomic number of sulphur?

In the electrolytic refining of metals, the insoluble impurities present in the impure metal settle down at the bottom of the container below the anode. What is this called?

Give reasons for the following:
$(a)$ School bells are made of metals.
$(b)$ Electrical wires are made of copper.