Which gas is characterized as the second lightest gas?

Helium is known as the second lightest gas, following hydrogen, which is the lightest. This classification is based on the atomic weights of the gases; hydrogen has an atomic weight of approximately 1.008 g/mol, while helium has an atomic weight of about 4.0026 g/mol.

The characteristics of helium contribute to its wide usage, particularly in applications such as balloon filling and as a coolant in cryogenics. Helium is non-toxic, non-flammable, and lighter than air, which makes it stable and safe for various medical and recreational uses.

While nitrous oxide, nitrogen, and hydrogen have their respective uses and characteristics, they are heavier than helium or do not hold the position of being the second lightest. Nitrous oxide, for example, is used primarily as an anesthetic and has a different molecular weight. Nitrogen, while abundant and important in many industrial processes, is heavier than helium, and hydrogen, as the lightest gas, precedes helium in this classification. Understanding these properties is vital for safe handling and application, especially in medical settings where gas characteristics affect storage and safety protocols.