Which material from the table is a liquid at 50°C and a gas at 300°C?

Answer:
Phosphorus
Explanation:
Melting point is the exact temperature where it changes from solid to liquid. So if the temp 50°C, it is higher than 44°C meaning that the element already melted and is staying as a liquid.
Boiling point is the exact temperature where it changes from liquid to gas. So if the temp 300°C, it is higher than 28°C meaning that the element already evaporated and is staying as a gas.