Glucose and mannose are

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

In fructose,the possible optical isomers are

Which of the following reactions of glucose can be explained only by its cyclic structure?

Which of the following carbohydrate$(s)$ would not undergo mutarotation in aqueous solution?

Hydrolytic conversion of sucrose into glucose and fructose is known as