Final answer:
The third most abundant element by mass on the Earth's surface is aluminum, with oxygen and silicon being the first and second most abundant elements respectively.
Step-by-step explanation:
The student asked which element is the third most abundant by mass on Earth's surface. To answer, we must consider the composition of the Earth's crust. By mass, the most abundant element in Earth's crust is oxygen, which constitutes approximately 46.1%, followed by silicon, making up 28.2%.
The third most abundant element by mass is actually aluminum, which makes up about 8.2% of the Earth's surface by mass.
It should be noted that while hydrogen is the most abundant element in the universe and is a major part of water on Earth, it does not make up a significant portion of the Earth's crust by mass due to its very low density. The majority of Earth's hydrogen is found in water (H₂O), and it's only about 0.14% of the Earth's crust by mass.