Total number of secondary amines (Excluding stereo isomer) possible with the molecular formula $C_5H_{13}N$ is

$P$ and $Q$ are isomers of dicarboxylic acid $C _4 H _4 O _4$. Both decolorize $Br _2 / H _2 O$. On heating, $P$ forms the cyclic anhydride.

Upon treatment with dilute alkaline $KMnO _4, P$ as well as $Q$ could produce one or more than one from $S , T$ and $U$.$Image$

$1.$ Compounds formed form $P$ and $Q$ are, respectively

$(A)$ Optically active $S$ and optically active pair $(T, U)$

$(B)$ Optically inactive $S$ and optically inactive pair $(T, U)$

$(C)$ Optically active pair $(T, U)$ and optically active $S$

$(D)$ Optically inactive pair $(T, U)$ and optically inactive $S$

$2.$ In the following reaction sequences $V$ and $W$ are respectively :$Image$

mcq $Image$

Give the answer question $1$ and $2.$

Which one of the compound is not isomer of others?

The stereochemistry of this molecule is

The Fischer projection of $D$-erythrose is shown below.

(image)

$D$-Erythrose and its isomers are listed as $P , Q , R$, and $S$ in Column-$I$. Choose the correct relationship of $P , Q , R$, and $S$ with D-erythrose from Column $II$.

(image)

How are the following compounds related ?