Select the odd one out

Select odd one out for Heterotrophic bacteria.

Select odd one out on the basis of digestive functions of tongue.

Select odd one out w.r.t. autosomal recessive trait.

Select odd one out w.r.t. Australian marsupials.

Select odd one out w.r.t. Australian marsupials.

Select odd one out w.r.t. autosomal recessive trait.

Select odd one out which does not fit as required and justify your answer Fe, Zn, Mg, Au " " Corrosion

Select odd one out from the following list of compounds. Formic acid, Nitric acid, Acetic acid, Propanoic acid.