One.
All whole numbers yes
All whole numbers have factors.
1
Yes.
It is not possible to express something as a sum of whole numbers with no common factor. All whole numbers have at least 1 as a common factor.
Two is a factor of all even numbers.
All whole numbers except for -1, 0 and 1 have at least one prime factor.
Yes, 5 is a factor of all whole numbers ending in 5.
Only 1.
One.
Yes. Five is a factor of all cardinal (whole) numbers ending in five
A whole number that is a factor of two or more numbers is a common factor.