Which of the following structures represent the same molecule?

Stereochemistry of the product is

The most stable canonical structure of the given molecule is:

$P$ and $Q$ are isomers of dicarboxylic acid $C_4H_4O_4$. Both decolorize $Br_2/H_2O$. On heating,$P$ forms a 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 $U$.
$1.$ Compounds formed from $P$ 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:
Give the answer for question $1$ and $2$.

Match List-$I$ with List-$II$.

List-$I$ Isomeric pairs	List-$II$ Type of isomers
$A$. Propanamine and $N$-Methylethanamine	$I$. Metamers
$B$. Hexan-$2$-one and Hexan-$3$-one	$II$. Positional isomers
$C$. Ethanamide and Hydroxyethanimine	$III$. Functional isomers
$D$. $o$-nitrophenol and $p$-nitrophenol	$IV$. Tautomers

Choose the correct answer from the options given below:

How many chiral carbon atoms are present in $2-$Bromo$-3, 4, 5-$trimethylhexane?