Question

Arrange the following 3 pure substances in order of increasing melting points at 1 atmosphere of pressure:

a) Iron
b) Oxygen
c) Water
d) None of the above

Answer 1

Oxygen has the lowest melting point, followed by water, and then iron.

Step-by-step explanation:

The substances can be arranged in order of increasing melting points as follows:

1. Oxygen: Oxygen is a molecular element that exists as a gas at room temperature. It has weak intermolecular forces and therefore has a relatively low melting point.
2. Water: Water is a molecular compound that exists as a liquid at room temperature. It has stronger intermolecular forces compared to oxygen, resulting in a higher melting point.
3. Iron: Iron is a metallic element that exists as a solid at room temperature. It has the strongest metallic bonding, which leads to the highest melting point among the three substances.

Therefore, the correct order of increasing melting points is: Oxygen < Water < Iron.