Consider the following reactions
${\rm{A}} + \mathop {\mathop {{\rm{NaCl}}}\limits_{\scriptstyle{\rm{Little }}\atop \scriptstyle{\rm{ amount}}} + {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4} \to {\rm{Cr}}{{\rm{O}}_2}{\rm{C}}{{\rm{l}}_2} + {\rm{ Side Products }}}\limits_{{\rm{ }}}$
${\rm{Cr}}{{\rm{O}}_2}{\rm{C}}{{\rm{l}}_{2{\rm{ (Vapour) }}}} + {\rm{NaOH}} \to \;{\rm{B}} + {\rm{NaCl}} + {{\rm{H}}_2}{\rm{O}}$
$\;{\rm{B}} + {{\rm{H}}^ + } \to {\rm{C}} + {{\rm{H}}_2}{\rm{O}}$
The number of terminal 'O' present in compound 'C' is _____