Which non-metal element exists in a liquid state at room temperature?

Why does a magnesium ribbon start floating when it is placed in hot water?

Which among the following statements is incorrect for magnesium metal?

Why do ionic compounds have high melting points? State the reason.

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

When a copper wire is left in silver nitrate solution,it is observed that the solution turns bluish green.
$(a)$ Explain the observation.
$(b)$ Write the balanced chemical equation to represent the change taking place.