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.
Under Chapter 7 bankruptcy, you can have all or part of your debts discharged after your liquid assets are used to repay some of the debt. What are liquid assets? In your possession, you might have liquid assets. These are assets that can quickly be converted into cash, e.g. checking and savings accounts. Some of your liquid assets must be turned over to the courts to be distributed among your creditors as partial repayment of the debt you owe.