Atoms and Molecules — Science STD 9 — Question

1. Element A forms an oxide A₂O₅. Crossing the valencies, we can see that the valency of O(oxide) is -2 and that of element A is 5.

2. Formula of chloride of A:

$\text{Element/ Ion}\ \ \ \ \ \ \ \text{A}\ \ \ \ \ \ \text{Cl}^-\\ \ \ \ \text{Valency}\ \ \ \ \ \ \ \ \ \ \ \ \ \ 5\ \ \ \ -1$

Formula of the chlcride of element A can be worked out by crossing over the valencies. Thus, the formula is ACl₅