Plural nouns take plural verbs.
A singular noun takes a singular verb.
These two sentences are simple examples.
But what happens when it’s a compound noun rather than a simple noun?
Bad Example: “Permeability and porosity is being measured in the lab.”
Here you have two things, permeability and porosity, being measured, so even though each of these nouns is singular, together they take a plural verb.
Corrected Example: “Permeability and porosity are being measured in the laboratory.”
(Yes, we spell out the word “laboratory” unless it is part of the proper name of a company.)
Consider the word “and” to be a wedding ring. When it binds two nouns into a compound subject, the two singles become a couple and need to take a plural verb — as long as they both shall live.
Ah, how romantic!