Answer: [tex]NaOH[/tex]
Explanation: Binary compound is a substance composed of exactly two different elements.
[tex]H_2O[/tex] is a binary compound as it is made up of hydrogen and oxygen atoms.
[tex]NaCl[/tex] is a binary compound as it is made up of sodium and chlorine atoms.
[tex]NaOH[/tex] is a not a binary compound as it is made up of three different elements i.e sodium, oxygen and hydrogen.
[tex]CH_4[/tex] is a binary compound as it is made up of carbon and hydrogen atoms.
