What is the oxidation number for the following atoms or ions?

a$)C{u}^{2+}$

b$)S^{2-}$

c$)P$

d$)T{i}^{4+}$

e$)H_2$

f$)A{g}^{+}$

g$)N^{3-}$

What is the oxidation number of the elements coloured in red in the compounds?

a$)H_{2}O$

b$)N{O}_2$

c$)PbS$

d$)C{H}_4$