<prompt> In ETC at which complex ATP is not formed -NADH CoQ reductaseSuccinate CoQ reductaseCoQ-cytochrome-C reductaseCytochrome C oxidase  <response>: Ans. is b i.e., Succinate CoQ reductase Complex I-IV Sites I-III of ATP formation in ETCComplex I: NADH CoQ-reductasePermit ATP formation Site IAct as proton pumpComplex II: Succinate CoQ reductaseNo ATP formComplex III; CoQ - cytochrome - C reductasePermit ATP formation Site IIAct as proton pumpComplex IV: Cytochrome C oxidasePermit ATP formation Site IIIAct as proton pump 