Photosynthesis of carbohydrates in plants takes place as

$6{\mathrm{CO}}_2 + 12{\mathrm{H}}_2\mathrm{O} \stackrel{\mathrm{Sunlight}}{\to } {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6 + 6{\mathrm{O}}_2 + 6{\mathrm{H}}_2\mathrm{O}$

Equivalent weights of ${\mathrm{CO}}_2 \mathrm{and} {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$ respectively are

$$\begin{gathered} \mathrm{Oxidation} \mathrm{number} \mathrm{of} \left(\mathrm{six} \mathrm{C}\right) 6\stackrel{+4}{\mathrm{C}}{\mathrm{O}}_2 \stackrel{ }{\to }{\stackrel{0}{ \mathrm{C}}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6 \\ \mathrm{Change} \mathrm{in} \mathrm{oxidation} \mathrm{number} =6\left(4\right)= 24 \mathrm{units} \\ \mathrm{Hence}, \mathrm{equivalent} \mathrm{weight} \mathrm{of} {\mathrm{CO}}_2 = \frac{6 \times 44}{24} = 11 \\ \mathrm{and} \mathrm{equivalent} \mathrm{weight} \mathrm{of} {\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6 = \frac{180}{24}=7.5 \end{gathered}$$