2-methyl propane on oxidation with `KMnO_(4)` gives

Toluene, on oxidation with KMnO_(4) gives

S_1 : 2-methylbutane on oxidation with KMnO_4 gives 2-methylbutan-2-ol S_2 : n-alkanes on oxidation with KMnO_4 gives alcohol

n - Butyl benzene on oxidation with KMnO_(4) gives

Ortho chlorotoluene on oxidation with KMnO_(4) gives :

Which alkene on oxidation with acidic KMnO_(4) gives only acetic acid?