Question

Which of the following is true about entropy?
a) It is a measure of how spread out thermal energy is within a system.
b) The entropy of the universe is at maximum at 0 K.
c) Entropy always increases in a spontaneous process.
d) The total entropy of the universe always decreases.

Answer 1

Entropy is a quantifiable physical characteristic that is most frequently linked with a condition of disorder, unpredictability, or uncertainty. The word and idea are utilised in a wide range of areas, from classical thermodynamics, where it was originally identified, through statistical physics' microscopic description of nature, to information theory's principles.

Complete answer:
(b) is wrong since it contradicts the third rule of thermodynamics because it is backwards.
The entropy of a flawless crystal at 0 K is zero, according to the third rule of thermodynamics. As a result, it should be around zero J/K at 0 K, indicating that it is "at" its minimum, not maximum.
(c) is wrong because it makes a claim that is far too broad to be accurate.
In a spontaneous process, entropy for the system OR the surroundings might drop, but either one could also rise.
The universe's absolute entropy, on the other hand, is continuously increasing.
The sign, and occasionally the actual value, of the enthalpy for that process at the same circumstances, as well as the sign of the entropy, affects spontaneity.
For example, a reaction at a high enough temperature with a negative system entropy is never spontaneous, but it can be spontaneous if the temperature is low and the enthalpy is big and negative.
(d) is wrong because it defies the second rule of thermodynamics, which states that the overall entropy of the cosmos rises with time.
(a) is the right answer.
The widely recognised (or, in my view, should be) definition of entropy is as follows:
The entropy is a measurement of how much energy is dispersed.
In other words, it's a metric for how energy may be dispersed across a chemical system, and it's fairly close to what we're looking for (a).

Note:
Aside from the need of not breaching the conservation of energy, which is represented in the fundamental rule of thermodynamics, entropy makes certain operations irreversible or impossible. The second rule of thermodynamics asserts that the entropy of isolated systems left to their own devices cannot decrease over time because they always arrive at a state of thermodynamic equilibrium, where the entropy is greatest.