Question

$2AlC{{l}_{3}}$ represents:
A. Two atoms of aluminum chloride
B. Two molecules of aluminum chloride
C. Three atoms of chlorine
D. Two atoms of aluminum

Answer 1

Aluminum chloride can also be known by some other names like aluminum trichloride or aluminum(III) chloride. The compound is formed when aluminum and chlorine are reacted together. Its chemical formula is written as $AlC{{l}_{3}}$. Aluminum chloride is generally white in colour but due to the presence of some contaminants like (iron(III) chloride) it acquires a yellowish colour.

Complete answer:
​$2AlC{{l}_{3}}$ represents two molecules or we can say two moles of Aluminium Chloride that will contain two molecules or two moles of Aluminium and six molecules or six moles of Chlorine. We cannot say two atoms of Aluminium Chloride as Aluminium Chloride is a compound composed of molecules.
A molecule is represented as an electrically neutral group of two or more atoms which are held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge. A molecule may be homonuclear which means it consists of atoms of one chemical element only for example ${{O}_{2}}$ or it may be heteronuclear in which a chemical compound composed of more than one element like molecule given in the question $AlC{{l}_{3}}$. While an atom can be defined as it is composed of a nucleus; nucleus is made up of protons and neutrons and electrons are revolving around the atom.

Hence we can say that $2AlC{{l}_{3}}$ represents two molecules of aluminum chloride, option B is the correct answer.

Note: Aluminium chloride is mainly used as a catalyst for different chemical reactions like in Friedel-Crafts reaction in both of its type acylation and alkylation. It is also used during the preparation of anthraquinone from phosgene and benzene and can be used to bring in or attach aldehyde groups on aromatic series or rings.