In photosynthesis, water (H2O) and carbon dioxide (CO2) react to form oxygen (O2) and glucose (C6H12O6). The following table shows the reactants and products of photosynthesis. What number should replace the question mark to show the number of C6H12O6 (glucose) molecules in a balanced chemical equation?

2

Explanation:

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.