Statement (i) is false because elements are made up of atoms (some of which combine to form molecules, while others like helium exist only as atoms), and compounds are made up of molecules formed by atoms of different elements. Statement (ii) is false because a compound is formed by atoms of different elements combining together, not the same kind. Statement (iii) is false because a molecule of nitrogen gas consists of two nitrogen atoms, not three. Statement (iv) is true as the context confirms that a water molecule (H₂O) contains two hydrogen atoms and one oxygen atom, held together by covalent bonds formed by sharing electrons.