### Video Transcript

Which of the following equations represents the first ionization energy of an element X? (A) X gas plus e minus produces X one plus gas. (B) X gas produces X one plus gas plus e minus. Or (C) X one plus gas plus e minus produces X gas.

To approach this question, we need to understand the definition of the first ionization energy of an element. The first ionization energy is the amount of energy needed to remove the most loosely bound electron completely from an isolated gaseous atom. An equation can be used to represent this process and follows the same pattern regardless of the element.

Let’s look at an example using the equation representing the first ionization energy of sodium. Sodium would be written as a reactant and in the gaseous state. In the products, sodium would have its most loosely bound electron removed, forming a sodium cation with a one-plus charge and the removed electron. Thus, the equation for the first ionization energy of an element contains the neutral gaseous element in the reactants and the gaseous one-plus cation of the element in the products as well as the lost electron. This pattern would hold true for any other element, even an unknown element X.

We can see that answer choice (B) matches this pattern. Therefore, the equation that represents the first ionization energy of element X is answer choice (B), where X gas produces X one plus gas plus e minus.