Which among the following sugars is called as laevulose?

Four carbohydrates: glucose,lactose,sucrose,and starch are present. Different tests are carried out with these $4$ carbohydrates separately. The following observations are made:
$(a)$ Heated: It is charred.
$(b)$ $I_2$ solution: No violet colour.
$(c)$ Fehling solution: Reddish brown precipitate is observed.
$(d)$ It does not reduce copper$(II)$ acetate to $Cu_2O$. No red precipitate is observed in $5 \ min$.
Which carbohydrate satisfies all the above observations?

What is the molecular formula of glyceraldehyde?

Which of the following structures is $L$-arabinose?

Which of the following does not show mutarotation?

The optical rotation of the $\alpha$-form of a pyranose is $+150.7^{\circ}$,that of the $\beta$-form is $+52.8^{\circ}$. In solution,an equilibrium mixture of these anomers has an optical rotation of $+80.2^{\circ}$. The percentage of the $\alpha$-form in the equilibrium mixture is $....... \%$.