The correct answer is D. The outermost shells of both are fully filled.
Helium and argon are both noble gases, which means that they have a full valence shell. This makes them very stable and unreactive. They are also both colorless, odorless, and tasteless gases. Helium is the second lightest element in the universe, after hydrogen. It is a monatomic gas that is lighter than air. Argon is the third most abundant element in the Earth’s atmosphere, after nitrogen and oxygen. It is also a monatomic gas that is slightly heavier than air.
Both helium and argon are used in a variety of applications. Helium is used in balloons, blimps, and dirigibles. It is also used in cryogenics, welding, and leak detection. Argon is used in arc welding, metal cutting, and semiconductor manufacturing. It is also used in lighting and as a protective gas for food packaging.
A. Both elements are liquid metals is incorrect. Helium is a gas at room temperature, while argon is a liquid at very low temperatures.
B. Both metals are used in balloons is incorrect. Helium is used in balloons, while argon is not.
C. Both have high diffusion rates is incorrect. Helium has a higher diffusion rate than argon.