Which of the following statements is incorrect for glucose?

The specific rotations of $\alpha-$ and $\beta-$ glucose are different. When either is dissolved in water,their rotation changes until a constant value is reached. This phenomenon is called ......

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.

Which of the following pentoses will be optically active?
$I$: $CHO-CH(OH)-CH(OH)-CH(OH)-CH_2OH$
$II$: $CHO-CH(OH)-CH(OH)-CH(OH)-CH_2OH$
$III$: $CHO-CH(OH)-CH(OH)-CH(OH)-CH_2OH$

The number of chiral carbon atoms present in the open-chain structure of $D-(-)$-fructose is:

Select the evidence for the open chain structure of glucose.