Entropy And Free Energy

To determine in which processes entropy increases, we need to understand what entropy means: it is a measure of disorder or randomness in a system. Entropy generally increases when the number of possible states or configurations of a system increases. Let's analyze each process:

1. A. A liquid evaporates to vapour.
   During evaporation, a liquid transforms into a gas. Gases have more disorder than liquids since the molecules in a gas move more freely and occupy a greater volume. Thus, entropy increases.
2. B. Temperature of a crystalline solid lowered from 130 K to 0 K.
   Lowering the temperature of a solid typically reduces its entropy as the molecular motion decreases, leading to a more ordered system.
3. C.
   This is a chemical reaction where solid sodium bicarbonate decomposes to form solid sodium carbonate, carbon dioxide gas, and water vapor. The formation of gases from a solid increases the entropy significantly since gases have a higher level of disorder.
4. D.
   The dissociation of chlorine gas into chlorine atoms increases entropy. Though both are in the gaseous state, forming more particles (from one mole of to two moles of ) leads to greater disorder.

Therefore, the correct answer is: A, C and D