What is the oxidation state of the indicated atoms in the following structure?

(i) 0

(ii) +1

(iii) 0

(iv) −2

(i) +2

(ii) +1

(iii) −1

(iv) −2

(i) −1

(ii) −1

(iii) 0

(iv) +2

(i) −2

(ii) −1

(iii) +1

(iv) +2