Answer:
1.Sign={}
•In mathematics, the empty set is the unique set having no elements; its size or cardinality is zero. Some axiomatic set theories ensure that the empty set exists by including an axiom of empty set, while in other theories, its existence can be deduced
2.Infinite set=uncountable
•In set theory, an infinite set is a set that is not a finite set. Infinite sets may be countable or uncountable
3.Finite set=countable
•In mathematics, particularly set theory, a finite set is a set that has a finite number of elements. Informally, a finite set is a set which one could in principle count and finish counting. For example, {\displaystyle \{2,4,6,8,10\}} is a finite set with five elements.
4.Cardinality if sets=measured by the number of elememts it contains
•The size of a finite set (also known as its cardinality) is measured by the number of elements it contains. Remember that counting the number of elements in a set amounts to forming a 1-1 correspondence between its elements and the numbers in {1,2,...,n}.
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