How many double bond equivalents (degree of unsaturation) does a compound with the molecular formula $C_6H_{12}O_6$ possess?

$L$-isomer of tetrose $X$ $(C_4H_8O_4)$ gives positive Schiff's test and has two chiral carbons. On acetylation,$X$ yields triacetate. $X$ also undergoes the following reactions:
$X$ $\xrightarrow{HNO_3} A$ $\xrightarrow{NaBH_4} \underset{\text{Chiral compound}}{B}$
$X$ is $.......$.

Determine the $D$ and $L$ configuration for the carbohydrates shown in the image.

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

Identify the false statement from the following.

Which of the following is a reducing sugar?