Write any two reactions of glucose which cannot be explained by the open chain structure of glucose molecule.

(1) Aldehydes give 2, 4-DNP test, Schiff's test, and react with NaHSO4 to form the hydrogen sulphite addition product. However, glucose does not undergo these reactions (2) The pentaacetate of glucose does not react with hydroxylamine. This indicates that a free -CHO group is absent from glucose.