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

Which of the following ores is in the form of oxide?

Which process occurs at the cathode during the process of electrolysis?

Why is hydrogen gas not evolved when a metal reacts with nitric acid?

By which method/process is sulphur obtained from the earth's crust?

Give reasons for the following:
$(i)$ Ionic compounds have high melting and boiling points.
$(ii)$ Ionic compounds are soluble in water.
$(iii)$ Ionic compounds are solid and somewhat hard.
$(iv)$ Ionic compounds conduct electricity in the molten state.
$(v)$ Metals have a tendency to lose electrons.