(a) The deficiency of vitamin D and lack of calcium in any child's diet causes rickets. As both vitamin D and calcium is important for healthy bones. (b) Example of fibrous protein is $\alpha$-keratin. Hairs, nails and collagens majorly contains this protein. Example of globular protein is haemoglobin; it plays the main role in carrying oxygen in the blood. (c) Gluconic acid $(\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_7)$ On reacting glucose with bromine water, glucose undergoes oxidation reaction to form gluconic acid as a product.