Question

an element X forms an oxide with formula X2O3 state the valency of X,write the formula of chloride of X and sulphate of X. Why can't X be gold or uranium ?

Answer 1

Aluminium is element X
Alcl3
Al2(so4)3

Answer 2

The element is Aluminium .
Valency : 3
Chloride : $AlCl_{3}$
Sulphate : $Al_{2}$$(S[tex] O_{4}$)_{3} [/tex]

And for the last question , I'm not sure .