An element X forms an oxide with formula X2O3. (A) State the valency of X
(B) Write the formula of:
i) Chloride of X. ii) Sulphate of X.

(A) The valency of element X can be determined from the formula of the oxide X2O3.

In X2O3, the subscript 2 indicates that there are two atoms of element X, and the subscript 3 indicates that there are three atoms of oxygen (O). To balance the charges in a chemical compound, we can use the crisscross method.

The valency of oxygen (O) is typically 2-, meaning it gains two electrons to achieve a stable electron configuration. Therefore, to balance the charges, element X must have a valency of 3+ (loses three electrons) because there are three oxygen atoms. So, the valency of X is +3.

(B) Now, let's write the formulas for the chloride and sulfate of X:

i) Chloride of X: Since the valency of X is +3, it will form a chloride by losing three electrons to achieve a stable electron configuration. Chlorine (Cl) has a valency of 1-. To balance the charges, we need three chloride ions for every one X ion. Therefore, the formula for the chloride of X is XCl3.

ii) Sulfate of X: Sulfate ions have a valency of 2-. To balance the charges, we'll need two sulfate ions for every one X ion with a valency of +3. Therefore, the formula for the sulfate of X is X2(SO4)3.