What's the plural form of regioselectivity? Here's the word you're looking for.
Answer
The noun regioselectivity can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be regioselectivity.
However, in more specific contexts, the plural form can also be regioselectivities e.g. in reference to various types of regioselectivities
or a collection of regioselectivities.