Which of the following reagents is used to identify the straight chain of glucose?

Given below are two statements: one is labelled as Assertion $A$ and other is labelled as Reason $R.$
Assertion $A :$ Sucrose is a disaccharide and a non-reducing sugar.
Reason $R :$ Sucrose involves glycosidic linkage between $C_{1}$ of $\beta$-glucose and $C_{2}$ of $\alpha$-fructose.
Choose the most appropriate answer from the options given below :

For the below given cyclic hemiacetal $(X)$,the correct pyranose structure is.

The product obtained in the reaction is:

What are $\beta - D - \text{glucose}$ and $\beta - D - \text{galactose}$ known as in relation to each other?

On hydrolysis,which of the following carbohydrates gives glucose only?