Cellulose is a linear polymer of  $\beta -\text{D}-$ glucose in which  ${\text{C}}_1$ of one glucose unit is connected to  ${\text{C}}_4$ of the other through  $\beta -\text{D}-$ glucosidic linkage. It does not undergo hydrolysis easily. However on heating with dilute  ${\text{H}}_2\text{S}{\text{O}}_4$ under pressure. It does undergo hydrolysis to give only D- glucose.

  ${\left({\text{C}}_{\text{6}}{\text{H}}_{\text{10}}{\text{O}}_{\text{5}}\right)}_{\text{n}}+{\text{nH}}_{\text{2}}\text{O}\stackrel{{\text{H}}^{+}}{\to }\underset{\text{D}-\text{Glucose}}{{\text{nC}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_6}$