Borax is heated in a bunsen burner flame with a compound X on a loop of platinum wire. A blue colored bead of compound Y is formed. Identify X and Y.

The borax bead test can be used to identify transition  metals as their metaborates have characteristic colours. CoO(X) on a loop of platinum wire, a blue colored Co(BO2)2 (Y) bead is formed. Therefore, X and Y are CoO and Co(BO2)2 respectively and the correct option is (b).