Question

The formula of aluminium oxide is $A{l}_2$$O_3$. If aluminium forms its chloride, what will be the formula of that compound?​

• A. AlCl
• B. $AlC{l}_2$
• C. $AlC{l}_3$
• D. $A{l}_{3}Cl$

Answer 1

The correct option is C $AlC{l}_3$

In $A{l}_2$$O_3$, the valency of aluminium is 3 and oxygen is 2.​

​
Valency of chlorine is 1.​

So, for chloride of aluminium:​

​
Symbol: Al Cl​

Valency: 3 1​

On interchanging the valencies of each element and writing them down as subscripts, we get the formula - $AlC{l}_3$.​