The specific rotation of equilibrium mixture of the three forms of glucose is:

52.5

The answer is (2) 52.5.

When glucose is dissolved in water, it undergoes a process called mutarotation, in which the alpha and beta anomers interconvert. The equilibrium mixture of the three forms of glucose has a specific rotation of +52.5°.

The specific rotations of the alpha and beta anomers of glucose are +112° and +19°, respectively. The specific rotation of the equilibrium mixture is calculated as the weighted average of the specific rotations of the individual anomers, taking into account their relative abundance in the equilibrium mixture.