Question

At room temperature, oxygen is a gas while water is a liquid. Why?

Answer 1

Hint: The room temperature is defined as the temperature of an indoor setting with the range of ${20}^{\circ }C-{25}^{\circ }C$ . At room temperature, various items exist in different states. The difference between the states is due to the intermolecular force of attraction.

Complete answer:
There exists an intermolecular force of attraction between the molecules of a substance which determines the state of that substance at different temperatures.
There is oxygen in one corner of the water, and two hydrogens protrude from each other at an angle. Because oxygen has many more protons than hydrogen and the opposite charge attracts each other, it moves electrons slightly away from hydrogen atoms, making oxygen negatively charged and each hydrogen positively charged. They form a V where the angle is negatively charged and the ends are positively charged. Because opposites attract, the next $H_{2}O$ tends to fit into the first V as an inverted V. Then the next $H_{2}O$ stretches the chain to the right and up. Water molecules like to form stacked alternating chains of Vs. The high temperature will shake these chains, but at room temperature, the water molecules are very viscous between them, they remain liquid, only a few water molecules evaporate accidentally, while oxygen molecules, without this viscosity, remain gaseous.
At room temperature, oxygen is a gas and water is a liquid because the force of attraction between oxygen molecules is less than the force of attraction between water molecules.
Therefore, water molecules are tightly bound to each other at room temperature.

Note:
Another way to explain this is - The room temperature is 25 degrees Celsius, which means that the boiling point of water is 100 degrees Celsius and the melting point is 0 degrees Celsius, so it means that water is a liquid at room temperature, and oxygen is a gas at room temperature.