An element B shows valencies of 4 and 6. Write the formulae of its two oxides.

When the element B shows the valency of 4,

Valency of B = 4

Valency of O = 2

Elements:  B       O

Valency:     4      2

Formula for the oxide formed by the element B (valency 4) can be worked out by crossing over the valency of the constituent elements.

Therefore, formula of the oxide of element B is B₂O₄.

The formula has a common factor of 2;

Hence, on dividing the formula by the common factor gives us the simplest chemical formula: BO₂.

When the element B shows the valency of 6,

Valency of B = 6

Valency of O = 2

Elements : B         O

Valency   : 6          2

Formula for the oxide formed by the element B (valency 6) can be worked out by crossing over the valency of the constituent elements.

Therefore, formula of the oxide of element B is B₂O₆.

The formula has a common factor of 2;

Hence, dividing the formula by the common factor gives us the simplest chemical formula: BO₃.