What are $\alpha - D -$ glucose and $\beta - D -$ glucose to each other?

Which of the following reactions of glucose can be explained only by its cyclic structure?

Given below are two statements. One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Amylose is insoluble in water.
Reason $R$: Amylose is a long linear molecule with more than $200$ glucose units.
In the light of the above statements,choose the correct answer from the options given below.

Sugar is the main source of energy as it produces energy on metabolic decomposition. But these days low calorie drinks are more popular,why?

Sugar which does not give reddish brown precipitate with Fehling's reagent is:

Identify the molecular formula of laevulose.