Where does $ETS$ occur in our body?

In oxidative photophosphorylation,the last $3$ steps are as follows: $Q \to C \to aa_3 \to O_2$. Which of the following statements is correct regarding the proton $(H^+)$ movement?

The number of $ATP$ molecules produced through the electron transport system from the intermediates of a single turn of the Krebs cycle is ......... .

Which mineral elements are essential for the process of respiration?

Choose the correct combination of $A$ and $B$ in accordance with the $NCERT$ textbook.
The $NADH$ synthesised in ...$A$... is transferred into the mitochondria and undergoes oxidative ...$B$...

The enzymes required for $ETS$ are arranged in/on . . . . . . .