The number of elements in sn = 1 point on o n n!/2 o 2n which of the follovwing is a 1 point groupoid but not a semigroup? o.) o r) o (n, +) o z,-

Any doubt then you can ask.

no.of elements in Sn = n! so option a is correct. and in second question (Z,-) is not associative (check) so not semi group , hence option d is correct. if any doubt then ask

Option A Option D