The temperature at which a gas, when subjected to Joule-Thomson expansion, neither cools or heats up, is termed as the __________ temperature. Above this temperature the gas heats up on throttling and below this the gas cools down.

ANS:C - inversion

In the context of thermodynamics, "inversion" refers to a particular phenomenon observed during the expansion or compression of gases, especially when subjected to the Joule-Thomson effect. This effect describes the change in temperature of a gas when it is allowed to expand or contract freely without performing any work. Specifically, during Joule-Thomson expansion, a gas experiences a change in temperature as it expands through a valve into a region of lower pressure. However, at a certain temperature known as the inversion temperature, the gas experiences no change in temperature upon expansion or compression. Above the inversion temperature, the gas cools down as it expands, while below the inversion temperature, the gas heats up. At the inversion temperature itself, the effects of cooling and heating balance out, resulting in no net change in temperature. The concept of inversion is significant in various applications, such as refrigeration and liquefaction processes, where precise control of temperature changes during gas expansion or compression is essential.