$DNA$ molecule contains $4$ bases whose structures are shown below. One of the structures is not correct,identify the incorrect base structure.

Which of the following reagents cannot distinguish between glucose and fructose?

From the given following ($A$ and $B$) cyclic structures, those which will not react with Tollen's reagent are :

$A$ molecule of glucose reacts with $x$ molecules of phenylhydrazine to form osazone. The value of $x$ is.........

$\alpha-D$-Glucopyranose and $\beta-D$-Glucopyranose are:

Consider the following statements:
Statement-$I$: Cane sugar is a disaccharide of $\alpha-D$-glucose and $\beta-D$-fructose.
Statement-$II$: Milk sugar is a disaccharide of $\beta-D$-glucose and $\beta-D$-galactose.
The correct answer is: