No. It is not a group.
negetive integers are not closed under addition but positive integers are.
If you mean the set of non-negative integers ("whole numbers" is a bit ambiguous in this sense), it is closed under addition and multiplication. If you mean "integers", the set is closed under addition, subtraction, multiplication.
yes
No.
no
No. It is not a group.
The set of positive integers does not contain the additive inverses of all but the identity. It is, therefore, not a group.
The set of integers, under addition.
negetive integers are not closed under addition but positive integers are.
Because the set is not closed under addition. If x and y are odd, then x + y is not odd.
If you mean the set of non-negative integers ("whole numbers" is a bit ambiguous in this sense), it is closed under addition and multiplication. If you mean "integers", the set is closed under addition, subtraction, multiplication.
Assuming that the question is in the context of the operation "addition", The set of odd numbers is not closed under addition. That is to say, if x and y are members of the set (x and y are odd) then x+y not odd and so not a member of the set. There is no identity element in the group such that x+i = i+x = x for all x in the group. The identity element under addition of integers is zero which is not a member of the set of odd numbers.
The numbers are not closed under addition because whole numbers, even integers, and natural numbers are closed.
yes
No.
Yes it is.