Law of corresponding states says that

• A. , two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same
• B. The surface of separation (i. e. the meniscus) between liquid and vapour phase disappears at the critical temperature
• C. No gas can be liquified above the critical temperature, howsoever high the pressure may be
• D. The molar heat of energy of gas at constant volume should be nearly constant (about 3 calories)