.

In this manner, can entropy be decreased?

It just says that the total entropy of theuniverse can never decrease. Entropy candecrease somewhere, provided it increases somewhere else by atleast as much. The entropy of a system decreases onlywhen it interacts with some other system whose entropyincreases in the process. That is the law.

what is the opposite of entropy? Negentropy is reverse entropy. It means thingsbecoming more in order. By 'order' is meant organisation, structureand function: the opposite of randomness or chaos. Oneexample of negentropy is a star system such as the Solar System.The opposite of entropy is negentropy.

Besides, is the entropy of the universe increasing or decreasing?

This statement is usually called the principle ofentropy increase. Irreversible or spontaneous processes canoccur only in that? direction for which the entropy of theuniverse or that of an isolated system, increases. Theseprocesses cannot occur in the direction of decreasingentropy.

Can entropy decrease in a closed system?

In a closed system, available energy cannever increase, so (because energy is conserved) its complement,entropy, can never decrease. A familiardemonstration of the second law is the flow of heat from hot thingsto cold, and never vice-versa. During this process, theentropy of the system increases.