Which of the following statements is true? question 5 options: the emission spectrum of a particular element is always the same and can be used to identify the element. the uncertainty principle states that we can never know both the exact location and speed of an electron. an orbital is the volume in which we are most likely to find an electron. all of the above are true.

All of the above are true

Explanation:

a) The emission spectrum of a particular element is always the same and can be used to identify the element: It's true since the emission spectrum for each element is unique. It has the same bright lines at the same wavelength. This feature is used to identify elements. For example, the study of the emission spectra of light arriving from stars allow us to identify the elements presents in the star because the light contains the emission spectra of those elements.

b)The uncertainty principle states that we can never know both the exact location and speed of an electron:  It is true since the velocity of an electron is related to its wave nature, while its position is related to its particle nature and we cannot simultaneously measure electron's position and velocity with precision.

c) An orbital is the volume in which we are most likely to find an electron: An orbital is a probability distribution map that is used to decribe the likely position of an electron in an atom.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)