Question

The oxidation state of aluminum is:
A. +3
B. +1, +2 and +3
C. +2 and +3
D. +1

Answer 1

Hint: the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom is called an oxidation state or number. It is a number that is assigned to an atom in a substance.

Complete step by step answer:
An oxidation number could be positive, negative or zero and it indicates if the electrons are lost or gained. Since metals are electropositive in nature aluminum exhibits a positive oxidation state.
Aluminum (i) is a monovalent aluminum its oxidation state is +1 in both ionic and covalent bonds and aluminum (ii) it is an extremely unstable form of aluminum. While aluminum (iii) is the much more common oxidation state of aluminum.
Hence Aluminum exhibits +1, +2 and +3 oxidation states.

Hence the option B is correct.

Note:
Aluminum (i) compounds are prone to disproportionation and difficult to prepare at standard conditions, they readily oxidize to aluminum (iii) form. Examples for aluminum (i) compounds of aluminum monofluoride are AlF, AlCl, AlBr these compounds are stable at high temperatures and low pressure only. Since Aluminum has three valence electrons so it will have the general oxidation state of +1, +2, and +3 oxidation state. The positive oxidation number indicates that the atom loses electrons and the atom undergoes oxidation.