Where does the $Krebs$ cycle take place?

When $1$ molecule of pyruvate is completely oxidized,how many moles of carbon dioxide are produced?

Pyruvic acid is converted into a compound before the formation of oxaloacetic acid in the citric acid cycle. This compound is:

In aerobic respiration,the citric acid cycle takes place in:

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

The product formed by malate dehydrogenase is