Identify monomials, binomials and trinomials in the given expression:
$-7$

Identify whether the given expression represents a monomial, binomial or trinomial.

$-5x^2{y}^2{z}^2$

Identify the following expression on the basis of the number of terms and write the degree:

$5a^2+b^2{c}^2+7$

Identify the following expression on the basis of number of terms and write the degree:

$9a^{2}bc$