Despite having the aldehyde group glucose does not give Schiff’s test and it does not form the addition product with  $NaHS{O}_3$. It undergoes oxidation with  $B{r}_2+H_{2}O, HI{O}_4 Conc.HN{O}_3.$ It also undergoes condensation with phenyl hydrazine and  $N{H}_{2}OH$.