10 ml 0.1 M $\text{Ca}{\left({\text{H}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}$ (assume complete solubility) and 10ml 0.1 M ${\text{KMnO}}_4$ are mixed in hot permanganate ion is :

No. of meq of ${\text{KMnO}}_4$ ${\text{KMnO}}_{\text{4}}\text{=\hspace{0.17em}10\hspace{0.17em}×\hspace{0.17em}0.1\hspace{0.17em}×\hspace{0.17em}5\hspace{0.17em}=\hspace{0.17em}5\hspace{0.17em}meq}$

$\text{No.\hspace{0.17em}of\hspace{0.17em}meq\hspace{0.17em}of\hspace{0.17em}Ca}{\left({\text{HC}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}\text{\hspace{0.17em}=\hspace{0.17em}10\hspace{0.17em}×\hspace{0.17em}0.1\hspace{0.17em}×\hspace{0.17em}4\hspace{0.17em}=4\hspace{0.17em}meq}$

$\underset{\text{4\hspace{0.17em}meq}}{\text{Ca}{\left({\text{HC}}_{\text{2}}{\text{O}}_{\text{4}}\right)}_{\text{2}}}\to \underset{\text{4\hspace{0.17em}meq}}{{\text{CO}}_{\text{2}}}$

${\text{4m\hspace{0.17em}eq\hspace{0.17em}CO}}_{\text{2}}\Rightarrow {\text{\hspace{0.17em}4\hspace{0.17em}m\hspace{0.17em}moles\hspace{0.17em}CO}}_{\text{2}}$

$\therefore {\text{1\hspace{0.17em}meq\hspace{0.17em}KMnO}}_{\text{4}}\text{\hspace{0.17em}is\hspace{0.17em}left\hspace{0.17em}}\Rightarrow \text{\hspace{0.17em}1/5m.\hspace{0.17em}mole\hspace{0.17em}is\hspace{0.17em}left}$