Generally for group 16 elements, like oxygen, sulphur, selenium.
The common oxidation number of manganese are +2, +4 and +7.
The most common oxidation number of magnesium is +2.
the most common oxidation number for oxygen is -2.
The most common oxidation number is +II. The charge and number for cobalt is +2.
The only oxidation number is 2+.
-2
The most common oxidation numbers are +1 and 2 , - 1 and 2.
2+
It depends on the compound. +1 and +2 are the more common ones (as in Cu2I2 and CuI2 respectively). In elemental form, its oxidation number is zero.
It is a gas. Generally it shows -2 oxidation number.
Cobalt is a transition metal. Its oxidation states are 2 (3).
+2 and +4