Air is mainly composed of nitrogen, oxygen, and argon, which together constitute the major gases of the atmosphere. Water vapor accounts for roughly 0.25% of the atmosphere by mass.
Physical property, such as real estate, does not qualify due to the unpredictable length of the sales process. As retirement accounts, 401(k)s and IRAs operate both as liquid assets and non-liquid assets depending on the circumstance.
If an asset is moderately (or very) liquid, it has moderate (or high) liquidity. In an alternative definition, liquidity can mean the amount of highly liquid assets. If a business has moderate liquidity, it has a moderate amount of very liquid assets. If a business has sufficient liquidity, it has a sufficient amount of very liquid assets and the ability to meet its payment obligations. An act of exchanging a less liquid asset for a more liquid asset is called liquidation.