Chemical Thermodynamics MCQs for NEET — Chemistry Questions with Answers

In an adiabatic process, there is no heat exchange with the surroundings. During adiabatic expansion, the system does work on the surroundings, and since no heat is added to the system, its internal energy decreases, resulting in a decrease in temperature.

When a refrigerator door is opened, the cooling system works harder to cool the extra warm air entering from the room. The heat extracted from the refrigerator's interior is released into the room, resulting in an overall increase in the room's temperature.

The cooling effect in a refrigerator is primarily due to the expansion of the refrigerant gas. When the gas expands, it absorbs heat from the refrigerator's interior, thereby cooling it.

An adiabatic process is a process in which no heat is transferred to or from the system. This means that during such a process, the total heat content of the system remains constant. This is in contrast to other types of processes like isochoric (constant volume), isobaric (constant pressure), and isothermal (constant temperature), where heat exchange can occur.

Warming ammonium chloride with sodium hydroxide in a test tube is an example of an open system. In an open system, both matter and energy can be exchanged with the surroundings. In this case, gases like ammonia may escape from the test tube, indicating the exchange of matter with the surroundings.

Intensive properties are those properties that do not depend on the amount of substance present. Out of the given options, boiling point (I), pH (III), and e.m.f. of a cell (IV) are intensive properties. Entropy (II), on the other hand, is an extensive property, as it depends on the amount of substance in the system.

A thermodynamic state function is a quantity whose value depends only on the state of the system, not on how the system got to that state. Examples include internal energy, enthalpy, and entropy. This means that the value of a state function is determined solely by the current state of the system, irrespective of the path taken to reach that state.

In thermodynamics, a process is called reversible when the surroundings are always in equilibrium with the system. This implies that the process can be reversed without leaving any change in either the system or the surroundings. In other words, the system and surroundings can be returned to their initial states with no net change.

Work is not a state function. Work depends on the path taken to reach one state from another, not just the initial and final states. Therefore, it is path-dependent. On the other hand, state functions like temperature, pressure, and volume depend only on the state of the system and not on how that state was achieved.

In an exothermic reaction like the combustion of carbon monoxide to carbon dioxide, the enthalpy change (ΔH) is typically greater than the change in internal energy (ΔE). This is because ΔH accounts for the heat released to the surroundings at constant pressure, which includes the work done by the system due to volume change. The relationship can be expressed as ΔH = ΔE + PΔV, where PΔV is the work done by the system. Since gases are involved, PΔV is positive, making ΔH greater than ΔE.