Mathematics for IGCSE & O level - Sets (Section 1 - No. 14)
Which statements describe properties of the empty set, represented by the symbol {} or ∅?
The empty set is a subset of every set.
The empty set is a set containing no elements.
The empty set is equal to the universal set.
The empty set has an infinite number of elements.
解释
Empty sets have no members and are a subset of every set.