Element Properties: Greenish Yellow Gas

This question requires identifying an element based on its described properties at room temperature: being a gas, having a greenish-yellow color, and possessing a specific smell.

Analyzing Element Characteristics

• State: The element is a gas.
• Color: The gas is greenish-yellow.
• Smell: It has a characteristic odor.
• Condition: These properties are observed at room temperature.

Matching Properties to Elements

Let's evaluate the options based on these properties:

• Chlorine (Cl): This element is indeed a greenish-yellow gas at standard temperature and pressure, known for its pungent, characteristic smell.
• Carbon monoxide (CO): This is a colorless and odorless gas.
• Iodine (I): This element is a solid at room temperature, although it can sublime into a purple vapor.
• Hydrogen sulphide (H₂S): This is a colorless gas, famous for its strong smell of rotten eggs.

Chlorine perfectly matches the description provided in the question.