Which of the following has the highest density?

Xe

The correct answer is option 4. Xe.

The density of an element is defined as its mass per unit volume. In the case of noble gases, density generally increases with increasing atomic mass. Let's break down why xenon (Xe) has the highest density among the noble gases listed:

Atomic Mass: Xenon (Xe) has the highest atomic mass among the noble gases provided in the options. The atomic masses of the noble gases listed are as follows:

Helium (He): ~4 atomic mass units (amu)

Neon (Ne): ~20 amu

Argon (Ar): ~40 amu

Xenon (Xe): ~131 amu

Relationship between Atomic Mass and Density: Generally, as the atomic mass of an element increases, its mass per unit volume (density) also increases, assuming the volume remains constant. This is because a greater mass distributed over the same volume results in higher density.

Comparison with Other Noble Gases: Helium (He) has the lowest atomic mass among the noble gases listed, resulting in the lowest density. Neon (Ne) has a higher atomic mass than helium but lower than argon and xenon, so its density is higher than helium but lower than argon and xenon. Argon (Ar) has a higher atomic mass than neon but lower than xenon, so its density is higher than helium and neon but lower than xenon. Xenon (Xe) has the highest atomic mass among the noble gases listed, resulting in the highest density among the options provided.

Conclusion: Due to its significantly higher atomic mass compared to helium, neon, and argon, xenon (Xe) has the highest density among the noble gases listed.

In summary, xenon's higher atomic mass results in a higher mass per unit volume, leading to a higher density compared to helium, neon, and argon. Therefore, xenon has the highest density among the options provided.