Mining Engineering Board Practice Exam

The density of the Earth's core is approximately 10.78 g/cm³, which is consistent with scientific measurements and studies of the Earth's internal structure. The core consists primarily of iron and nickel, which are dense metals, contributing significantly to this high density. The inner core is solid, while the outer core is molten, and both layers exhibit these high densities due to the immense pressure and temperature conditions found at such depths.

The other values provided do not align with current geological and geophysical knowledge. For instance, a density of 5.5 g/cm³ is associated with the Earth's crust and upper mantle, while 7.8 g/cm³ approximates the density of the Earth's upper layers. A density of 9.8 g/cm³ might seem plausible but still falls short of the actual measurements for the core's composition. The correct choice reflects an understanding of the core's composition and the extreme conditions it experiences, thereby facilitating an accurate grasp of Earth's internal structure.