Final answer:
Barium hydroxide (Ba(OH)2) is an example of a hydroxide of an alkaline earth metal containing electrons in at least 4 energy levels.
Step-by-step explanation:
The question asks for a hydroxide of an alkaline earth metal that contains electrons in at least 4 energy levels. Group 2 of the periodic table, known as the alkaline earth metals, includes beryllium, magnesium, calcium, strontium, barium, and radium.
Since beryllium only has electrons in the 1s and 2s orbitals, it does not meet the criteria. However, elements such as calcium (Ca), strontium (Sr), and barium (Ba) do have electrons in at least 4 energy levels. Among these, barium hydroxide would contain electrons in the 1s, 2s, 2p, 3s, 3p, 4s, and even higher orbitals, because barium has an atomic number of 56. Therefore, barium hydroxide (Ba(OH)2) is an example that meets the criteria of having electrons in at least 4 energy levels.