Adiabatic compression is which of the following?

• A. An isothermal process
• B. One where there is an increase in kinetic energy
• C. One where there is no loss or gain of heat
• D. All of the above

Answer: (C)

Adiabatic means no heat is exchanged with the surroundings. In an adiabatic compression, the gas is insulated so heat cannot enter or leave (Q = 0). Any work done on the gas increases its internal energy, which for an ideal gas shows up as a rise in temperature and, therefore, higher molecular kinetic energy. The defining point is the absence of heat transfer, not whether the temperature changes. An isothermal process, by contrast, requires heat flow to keep the temperature constant, so it isn’t adiabatic. Saying there’s an increase in kinetic energy describes the usual outcome (temperature rise) but isn’t the defining feature of adiabatic compression.