Complete hydrolysis of cellulose gives

Solution :
Cellulose is a linear polymer of $$\beta - D - $$  glucose in which $${C_1}$$  of one glucose unit is connected to $${C_4}$$  of the other through $$\beta - D$$  glucosidic linkage. It does not undergo hydrolysis easily. However on heating with dilute $${H_2}S{O_4}$$  under pressure. It does undergo hydrolysis to give only $$D - $$ glucose.
\[\left( {{C}_{6}}{{H}_{10}}{{O}_{5}} \right)n+n{{H}_{2}}O\xrightarrow{H+}\underset{D\text{-Glucose}}{\mathop{n{{C}_{6}}{{H}_{12}}{{O}_{6}}}}\,\]