Chemistry - Nomenclature Question with Solution | TestHub

Given compounds are isomers having the same molecular formula, so statement (A) is correct.
Degree of unsaturation depends only on molecular formula, therefore all compounds also have the same DU, so (B) is correct.
Some compounds may contain double bond/triple bond (unsaturated) while some may be cyclic compounds without multiple bonds (saturated but having same DU). Hence statement (D) is also correct.
Therefore, it is wrong to say that all compounds are unsaturated.
So statement (C) is incorrect.