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

If the valency of carbon is 4 and that of sulphur is 2, work out the formula of the compound formed by the combination of carbon with sulphur. What is the name of this compound?

An element X has a valency of 4 whereas another element Y has a valency of 1. What will be the formula of the compound formed between X and Y?

An element X of valency 3 combines with another element Y of valency 2. What will be the formula of the compound formed?

Work out the formula for magnesium hydrogencarbonate.