Comprehensive Analysis of Set-Builder Notation

Given that

\({\xi = \{x : x\text{ is an integer such that}\hspace{0.5em} 0 \leq x \leq 14\}}\)

\({A = \{x : x\text{ is a prime number}\hspace{0.15em}\}}\)

\({B = \{x : x\text{ is a factor of 28}\hspace{0.15em}\}}\)

\({C = \{x : \sqrt{x}\text{ is a positive integer}\hspace{0.15em}\}}\)

1. Find \(n(C')\),
2. List the element(s) of the set \((A \cap B)\).

All sets in this question are subsets of the stated universal set \(\xi\); every set-builder variable is restricted to that universe.