$\alpha - D - (+)$ glucose and $\beta - D - (+)$ glucose are

The number of stereoisomers of aldoheptose is $a$ and the number of stereoisomers of ketoheptose is $b$. The ratio of $a/b$ 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 ....

The following carbohydrate is

Which of the following statements is not correct for glucose?

Which of the following represents a nucleoside of $RNA$?