Are the following statements true or false?
(a) 2∈S, where S={x∈R∣x is the square root of an integer }
(b) ∅∈{∅}
(c) ∅⊂∅
(d) {{∅}}⊂{∅,{∅}}
(e) {∅,{∅},{∅,{∅}}} has the cardinality 4 .
(f) {∅,{a},{∅,a}} is the powerset of a set of cardinality 2 .
(g) If A,B, and C are sets such that A∪C=B∪C and A∩C=B∩C then A=B.