Question

Select the correct statement among the following:

• A. Helium has the lowest melting point and boiling point.
• B. Neon, argon, krypton and xenon form clathrates.
• C. Helium can diffuse through rubber, PVC and even glass.
• D. All the noble gases are monoatomic.
• E. All the noble gases have negative electron gain enthalpy.

Answer 1

Answer: (A), (C), (D)

The correct options are
A Helium has the lowest melting point and boiling point.
C Helium can diffuse through rubber, PVC and even glass.
D All the noble gases are monoatomic.

• Among noble gases, helium has the lowest boiling point (4.2 K) and melting point (0.95 K).
• Clathrates (or cage compounds) are compounds of noble gases in which they are trapped within cavities of crystal lattices of certain organic and inorganic substances. Ar, Kr and Xe can form clathrates, but He and Ne cannot fit because of their small size.
• Helium has an unusual property of diffusing through most commonly used laboratory materials such as rubber, glass or plastics.
• Noble gases have high ionisation enthalpy and more positive electron gain enthalpy.