Identify $B$ in the following tautomerization reaction:
$4\text{-pyridone} \xrightarrow{KOH} B$

Which of the following compounds has a center of symmetry?

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

Which of the following compounds does not undergo base-catalyzed exchange in $D_2O$ even though it has an $\alpha$-hydrogen?

Consider the following structures. Which statement is $NOT$ correct?

$A$ pair of stereoisomers might be classified in various ways. Which of the following statements are true with respect to pairs of stereoisomers?
$a$. They might be configurational isomers
$b$. They might be diastereomers
$c$. They might be constitutional isomers
$d$. They might be tautomers
$e$. They might be conformational isomers
$f$. They might be enantiomers
$g$. They might be positional isomers