Integral Domain iff Zero Ideal is Prime

Theorem

Let $A$ be a commutative ring with unity.

The following are equivalent:

1. $A$ is an integral domain
2. the zero ideal $0 \subseteq A$ is prime

Proof

By Prime Ideal iff Quotient Ring is Integral Domain, $0$ is prime if and only if the quotient ring $A/0$ is an integral domain.

By Quotient Ring by Null Ideal, $A \cong A / 0$.

$\blacksquare$