Starch,when boiled with dilute sulphuric acid under high pressure,gives compound $A$. On prolonged heating with hydroiodic acid,$A$ gives compound $B$. What is the compound $B$?

The structures of cyclic $D$-glucoside are given. Determine the moles of $HIO_4$ consumed by $X$ and $Y$ respectively.

In the 'glycolipids',the two sugars known to occur are glucose and

On complete hydrolysis of starch,we finally get

Sugar $X$:
$A.$ is found in honey.
$B.$ is a keto sugar.
$C.$ exists in $\alpha$ and $\beta$-anomeric forms.
$D.$ is laevorotatory.
$X$ is

$L$-isomer of a compound $A$ $(C_{4}H_{8}O_{4})$ gives a positive test with $[Ag(NH_{3})_{2}]^{+}$. Treatment of $A$ with acetic anhydride yields a triacetate derivative. Compound $A$ produces an optically active compound $B$ and an optically inactive compound $C$ on treatment with bromine water and $HNO_{3}$ respectively. Compound $A$ is ....