Which reaction proves that all the six carbon atoms are linked in a straight chain in glucose?

Glucose and fructose form:

If $\alpha-D-(+)$-glucose is dissolved in water and kept for a few hours,the major constituent$(s)$ present in the solution is (are)

Which of the following is correct?
Pentaacetate of glucose $\xrightarrow{\text{Tollen's reagent}} +ve$ test $(A)$
Pentaacetate of glucose $\xrightarrow{\text{Benedict's reagent}} +ve$ test $(B)$
Pentaacetate of glucose $\xrightarrow{\text{Schiff's reagent}} -ve$ test $(C)$
Pentaacetate of glucose $\xrightarrow{NaHSO_3} -ve$ test $(D)$

What are the two forms of $D$-glucopyranose obtained from a $D$-glucose solution called?

Which reagent forms a crystalline osazone derivative upon reaction with glucose?