In chemical nomenclature, prefixes are primarily used to indicate the number of atoms of each element present in a compound. The correct answer is: Prefixes are used to tell how many of each kind of atom are in covalent compounds.
The correct answer is option B.
In covalent compounds, which consist of nonmetals bonding through the sharing of electrons, prefixes are employed to specify the quantity of each type of atom. This is particularly crucial when dealing with molecular compounds, where multiple atoms of the same element may be present. For example, in the compound carbon tetrachloride (CCl₄), the prefix "tetra-" indicates the presence of four chlorine atoms.
On the other hand, in ionic compounds, which involve the transfer of electrons between metals and nonmetals, the use of prefixes is generally not applicable. Instead, numerical prefixes are often unnecessary, as the charges of the ions involved determine the ratio of elements in the compound.
In summary, prefixes play a key role in naming covalent compounds by specifying the number of each type of atom present in the molecule. This distinction is important for accurately representing the composition of molecular substances, ensuring clarity in chemical communication.
Therefore , from the given options the correct one is B.