Vitamin $C$ is

Which one of the following vitamins contains a metal atom?

In a water molecule,at what angle are the $H - O - H$ bonds connected (in $^\circ$)?

Complete the following analogy-type questions:
$(i)$ Purine : Guanine :: Pyrimidine : .........
$(ii)$ Hexokinase : Transferase :: Amylase : .........

$A$: Dextrins are intermediate polysaccharides formed during the hydrolysis of starch into sugar.
$R$: Ascorbic acid is a sugar derivative.

Water soluble vitamins are