State whether the following expression is a numerical expression or an algebraic expression.

$11a^2+6b^2-5$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$y^2$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$4y-7z$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$1+x+x^2$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$7mn$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$a^2+b^2$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$100xyz$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$ax+9$

State whether the algebraic expression given below is monomial, binomial, trinomial or multinomial.

$p^2-3pq+r$