How do yout explain the presence of five `-OH` groups in glucose molecule?

Explanation

Glucose on reaction with acetic anhydride produces glucose pentaacetate.
`overset(" "CHO)overset(|)underset(" "CH_(2)OH)underset(|)(" "(CHOH)_(4))overset("Acetic anhydride")rarroverset(" "CHO)overset(|)underset(" ""Glucose pentacetate")underset(" "CHOAc)underset(|)(" "(CHOAc)_(4))`
This reaction explain presence of five -`OH` groups.