Sucrose on hydrolysis gives

$L$-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 $.......$.

The standard compound for determination of configuration in the 'sugar chemistry' is

Which one of the following is laevorotatory?

Which among the following is a product of hydrolysis of one mole of raffinose?

Which is not a reducing sugar?