Galactose is converted into glucose in

Which of the following is an aldohexose?

Which of the following is not a biopolymer?

Glucose will show mutarotation when the solvent is

Which of the following are reducing sugars?
$I$. Sucrose
$II$. Ribose
$III$. Lactose
$IV$. Fructose

Compound $A$,$C_5H_{10}O_5$,gives a tetraacetate with $Ac_2O$ and oxidation of $A$ with $Br_2-H_2O$ gives an acid,$C_5H_{10}O_6$. Reduction of $A$ with $HI$ gives isopentane. The possible structure of $A$ is: