Chuck wants to know how many electrons in an atom are not paired up. which model would be best for chuck to write out?

a set of quantum numbers for the last electron in the atom
a configuration with numbers, letters, and superscripts
a dot structure of the atom
an orbital notation of the atom

The best model which Chuck will use is an orbital notation of the atom.

Explanation: Orbital notation of an atom is described as the arrangement of electrons in the orbitals present in an atom.

This is also known as the electron configuration.

This notation follows Hund's rule which states that the every orbital in the given subshell will be singly occupied first, until one electron gets paired up.

So, the orbital notation of an atom will make Chuck know how many electrons are not paired up.

The model, which will be best for Chuck to use is AN ORBITAL NOTATION OF THE ATOM.

An orbital notation refers to a mean of writing the electronic configuration of elements in such a way that they provide more detailed information about the electrons that are present in an element. Orbital notation uses blank to represent orbitals and arrows to represent electrons. Orbital notation can also be used to determine the quantum number of an electron.

the volume of fluid displaced would equal the volume of the gas. use a gas syringe - this is a laboratory instrument that can be used to withdraw a certain volume of gas from a closed system or to measure the volume of gas from a chemical reaction.