Question

The valency of an element A is 3 and element B is 2. Write the formula of the compound formed by combination of A and B?

Answer 1

A chemical compound is a material made up of numerous similar molecules (or molecular entities) that are bound together by chemical bonds and contain atoms from many elements. As a result, a molecule made up of only one element's atoms is not a compound.
Depending on how the component atoms are kept together, there are four types of compounds:
Covalent bonding holds molecules together.
Intermetallic compounds held together by metallic bonds specific complexes held together by coordinate covalent links ionic compounds held together by ionic bonds

Complete answer:
A chemical formula is a means of presenting information on the chemical quantities of atoms that make up a chemical compound or molecule using chemical element symbols, numbers, and other symbols like parentheses, dashes, brackets, commas, and plus (+) and minus (-) signs. These are restricted to a single typographic line of symbols, including subscripts and superscripts. A chemical formula isn't the same as a chemical name, and it doesn't have any words in it. A chemical formula may suggest certain basic chemical structures, but it is not the same as a complete chemical structural formula.
In chemistry, an element's valence is a measure of its ability to combine with other atoms to create chemical compounds or molecules. The amount of hydrogen atoms that an atom of a certain element may combine with determines its combining capability, or affinity. Carbon has a valence of 4 in methane; nitrogen has a valence of 3 in ammonia; oxygen has a valence of 2 in water; and chlorine has a valence of 1 in hydrogen chloride. Because chlorine has a valence of one, it may be used to replace hydrogen.
You may be aware that when two atoms, such as O and Fe, are combined, their valencies are swapped. The value of O is 2, and the value of Fe is several, but we'll use 3 as an example. As a result, $F{{e}_{2}}{{O}_{3}}$ would be the answer.
All you have to do now is repeat the process with elements A and B.

A tends to be 3, B tends to be 2; so the formula is ${{A}_{2}}{{B}_{3}}$

Note:
Chemical formulas can be used to explain chemical reactions and other chemical transformations, such as the dissolution of ionic substances into solution, in chemical equations. While chemical formulae do not have the full power of structural formulae to depict chemical relationships between atoms, they are sufficient to keep track of the number of atoms and electrical charges in chemical reactions, thus balancing chemical equations and allowing them to be used in chemical problems involving atom conservation and electric charge conservation.