Which of the following expressions are polynomials in one variable and which are not? State reasons for your answer: $y^{2} + \sqrt{2}$

(A) The given expression is $y^{2} + \sqrt{2}$.
This can be written as $y^{2} + \sqrt{2}y^{0}$.
$A$ polynomial in one variable is an algebraic expression where the exponent of the variable is a non-negative integer (a whole number).
In the expression $y^{2} + \sqrt{2}$,the exponent of the variable $y$ is $2$,which is a whole number.
Therefore,$y^{2} + \sqrt{2}$ is a polynomial in one variable.