Which is a gas at room temperature?
A) aluminum
B) nitrogen
C) potassium
D) sodium
The Correct Answer and Explanation is:
The correct answer is B) nitrogen.
At room temperature, nitrogen exists as a diatomic gas (N₂), making it one of the several elements that are naturally in gaseous form under standard conditions. Nitrogen constitutes about 78% of the Earth’s atmosphere and is essential for life, though it is inert and non-reactive under normal conditions due to the strong triple bond between the nitrogen atoms.
Let’s break down why nitrogen is a gas at room temperature compared to the other elements listed:
- Nitrogen (N₂): Nitrogen has weak intermolecular forces between its diatomic molecules, primarily van der Waals forces, which do not require much energy to overcome. As a result, nitrogen molecules remain in a gaseous state at room temperature (around 20-25°C). Its boiling point is -195.8°C, far below room temperature, which ensures that it stays as a gas under normal conditions.
- Aluminum (Al): Aluminum is a solid at room temperature with a melting point of about 660.3°C. As a metal, aluminum has a crystalline structure where its atoms are tightly bound in a lattice by metallic bonds, which gives it a solid state.
- Potassium (K): Potassium is an alkali metal that is also solid at room temperature, though it has a lower melting point compared to many other metals (63.5°C). Potassium has metallic bonds that maintain its solid form until higher temperatures.
- Sodium (Na): Similar to potassium, sodium is another alkali metal that is solid at room temperature. It has a melting point of 97.8°C and remains solid under normal conditions. Like potassium, sodium’s metallic bonds keep it in a solid state at room temperature.
In summary, nitrogen is a gas at room temperature due to its weak intermolecular forces and low boiling point, while aluminum, potassium, and sodium are solids due to their strong metallic bonding structures.