c
\({{\text{N}}_{\text{1}}}{{\text{V}}_{\text{1}}}{\text{  =  }}{{\text{N}}_{\text{2}}}{{\text{V}}_{\text{2}}}\)

\({\text{50 }}\, \times {\text{ 36  =  }}{{\text{N}}_{\text{2}}}\,\, \times {\text{ 100}}\)

\( \Rightarrow {\text{ }}{{\text{N}}_{\text{2}}}{\text{  =  18}}\)

\(\because \,\,{\text{M}}\,\, \times \,\,{\text{n}}\,\, = \,\,{\text{N}}\,\, \Rightarrow \,\,{\text{M}}\,\, = \,\,\frac{{\text{N}}}{{\text{n}}}\,\, = \,\,\frac{{18}}{2}\,\, = \,\,9\)