What is the other name of group 18 elements? 

Noble gases 

The correct answer is option 1. Noble gases.

Group 18 elements are also commonly known as "Noble gases." Here's an explanation:

1. Electronic Configuration:  Noble gases have a full outer electron shell, meaning their outermost electron shell is completely filled with electrons. This configuration results in high stability because it satisfies the octet rule, which states that atoms tend to gain, lose, or share electrons to achieve a stable configuration with eight electrons in the outermost shell (except for hydrogen and helium, which strive to achieve a duet configuration with two electrons in the outer shell).

2. Low Reactivity: Due to their full outer electron shells, noble gases have little tendency to gain or lose electrons or to form chemical bonds with other elements. As a result, they exhibit very low reactivity under normal conditions. This makes them "noble" or inert compared to other elements. They are often found in their elemental form in nature.

3. Physical Properties: Noble gases are colorless, odorless, and tasteless gases at room temperature and pressure. They have low boiling and melting points, and they exist as monatomic gases (composed of single atoms) in their elemental state.

4. Applications: Despite their low reactivity, noble gases have several important applications. Helium, for example, is used in cryogenics, as a coolant in nuclear reactors, and in helium-filled balloons. Neon is famous for its use in neon lighting. Argon is commonly used in welding, as a shielding gas in the production of metals, and in lighting applications. Other noble gases like xenon and krypton have applications in lighting, medical imaging, and anesthesia.

5. Abundance: While noble gases are relatively rare in the Earth's atmosphere compared to other elements, they are more abundant in the universe, especially in stars.

In summary, noble gases are a group of elements characterized by their full outer electron shells, low reactivity, and various practical applications despite their inert nature. Their unique properties make them essential in various scientific, industrial, and commercial applications.