Is empty set subset to every set?

Empty set is

Theorem 1 (Every set is a subset of itself.Theorem 2( The empty set is a subset of every set)

Is any set subset to itself?

Which of the following statement(s) is/are true? (A) Every subset of an infinite set is infinite. (B) Every set has a proper subset. (C) Number of subsets of every set is even. (D) Every subset of a finite set is finite

Define subset of a set.

The number of non empty subsets of the set {1,2,3,4} is