Which of the following statements are true?
(i) Mn has highest oxidation state in \( \text{Mn}_2\text{O}_7 \)
(ii) \( \text{MnO} \) is more ionic than \( \text{Mn}_2\text{O}_7 \)
(iii) \( \text{Mn}_2\text{O}_7 \) has one bridging O atom
(iv) Oxidation state of Mn is generally maximum in oxo compounds