A single number is not the same as a set containing a single number.
A single number does not have any subsets.
pi is a single number , not a set. Since it is not a set, it cannot have a subset.
A number does not have a subset.
A set can have a subset, a number cannot - whether or not it is negative.
No, rational numbers are not a subset of integers.
A whole number is not a set of any kind and so cannot be a subset of rational numbers.
Yes, but not a proper subset: they are the same set.
A single number, such as 1368, is not sufficient to determine a rule.
It is not possible to determine an nth term from a single number.
The subset consisting of the one number, 7.5 : {7.5}
yes
Cardinality is simply the number of elements of a given set. You can use the cardinality of a set to determine which elements will go into the subset. Every element in the subset must come from the cardinality of the original set. For example, a set may contain {a,b,c,d} which makes the cardinality 4. You can choose any of those elements to form a subset. Examples of subsets may be {a,c} {a, b, c} etc.
No. There is one even prime.