Question

Which is not a binary compound? H2O NaCl NaOH CH4

Answer 1

Answer: $NaOH$

Explanation: Binary compound is a substance composed of exactly two different elements.

$H_2O$ is a binary compound as it is made up of hydrogen and oxygen atoms.

$NaCl$ is a  binary compound as it is made up of sodium and chlorine atoms.

$NaOH$ is a not a binary compound as it is made up of three different elements i.e sodium, oxygen and hydrogen.

$CH_4$ is a binary compound as it  is made up of carbon and hydrogen atoms.

Answer 2

NaOH is not a compound because it contains three instead of two.