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.
