Final answer:
Oxygen and silicon are the two elements that make up the greatest percentage of Earth's crust, with oxygen being the most abundant, followed by silicon.
Step-by-step explanation:
The two elements that make up the greatest percentage of Earth's crust are oxygen and silicon. Oxygen is the most abundant element, comprising about 46.6% by weight of the crust, and it is present mostly in combination with other elements. Silicon follows, making up approximately 27.7% of the crust's weight. Together, these two elements form various silicate minerals, which constitute the majority of Earth's crust. For example, granite, which is a common component of the continental crust, and basalt, which forms the oceanic crust, are both made up primarily of silicates, containing both oxygen and silicon.
According to the information provided, oxygen accounts for 94% of the crust by volume and 47% by weight, making it the most abundant element. Silicon accounts for 1% of the crust by volume and 28% by weight.