Question

The oxidation number of Ca in all its
compounds is​

Answer 1

O.N. of group IA element i.e. Li, Na, K etc is always +1 in their compounds. O. N. of group IIA elements i.e. Be, Mg, Ca, Sr and Ba are always +2 in their compounds. O. N. of F is always -1 in its compounds because it is most highly electronegative. Oxidation O. N. of other elements of group VIIA.

Answer 2

Oxidation number of Calcium is 20