Question

The oxidation state of $Al$ in $AlC{l}_3$ is

• A. -3
• B. +3
• C. +2
• D. -2

Answer 1

The correct option is B

+3

In compounds formed by union of metals with non-metals, the metal atoms will have positive oxidation numbers and the non-metals will have negative oxidation numbers. Also, the oxidation number of alkali metals ($Li,Na,K$ etc.) is always +1 and those of alkaline earth metals ($Be,Mg,Ca$ etc) is +2.

Let the oxidation number of Aluminum = n

The halogen atoms being much more electronegative, will have -1 oxidation state each.

$⟹$ n + 3$\times$(-1) = 0
Or n = +3