Acetyl $Co-A$ binds to oxaloacetic acid to form

The product formed by malate dehydrogenase is

Match the enzyme involved in the Krebs cycle given in column-$I$ with the reactions they catalyse given in column-$II$. Choose the correct option.

Column $I$	Column $II$
$i.$ Isocitrate dehydrogenase	$a.$ Citrate $\rightarrow$ Cis-aconitate
$ii.$ Fumarase	$b.$ Succinate $\rightarrow$ Fumarate
$iii.$ Aconitase	$c.$ Fumarate $\rightarrow$ Malate
$iv.$ Succinate dehydrogenase	$d.$ Isocitrate $\rightarrow$ Oxalosuccinic acid

Which is the $5C$ intermediate molecule in the $TCA$ cycle?

How many substrate-level $ATP$ (or $GTP$) molecules are synthesized when $\alpha$-ketoglutaric acid is converted into succinic acid in the Krebs cycle?

In which reaction is $NAD^+$ not reduced to $NADH + H^+$?