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 (approximately 20-25°C or 68-77°F), nitrogen exists as a gas. It is a diatomic molecule (N₂) and constitutes about 78% of the Earth’s atmosphere by volume. The physical properties of nitrogen at room temperature include being colorless, odorless, and tasteless, which makes it undetectable by human senses in its natural state.
In contrast, the other options listed—aluminum, potassium, and sodium—are all solid metals at room temperature. Here’s a brief overview of each:
- Aluminum (A): This metal has a melting point of about 660°C (1220°F) and is found in a solid state at room temperature. It is lightweight and commonly used in various applications, including construction, transportation, and packaging due to its resistance to corrosion and high strength-to-weight ratio.
- Potassium (C): Potassium is an alkali metal with a melting point of around 63.5°C (146.3°F). While it can be a solid at room temperature, it is soft enough to be cut with a knife and reacts vigorously with water, producing hydrogen gas and heat.
- Sodium (D): Similar to potassium, sodium is also an alkali metal, with a melting point of about 97.8°C (208°F). Sodium is a soft, silvery-white metal that reacts with water and is also solid at room temperature.
The distinction in states at room temperature is primarily due to the molecular structure and bonding of the elements. Nitrogen’s molecular structure, with its triple bond between the two nitrogen atoms, contributes to its gaseous state, as it requires more energy (in the form of heat) to change its state to liquid or solid compared to the metallic bonds in aluminum, potassium, and sodium.