Question

1. oxygen is the most abundant element by volume in earths a) troposphere b) inner core c) hydrosphere d) crust

Explanation:

To determine where oxygen is the most abundant element by volume in Earth's components, we analyze each option:

• Option A (Troposphere): The troposphere (lower atmosphere) has nitrogen (~78%) and oxygen (~21%) by volume, so oxygen isn’t the most abundant here.
• Option B (Inner Core): The inner core is mostly iron and nickel (metallic), with very little oxygen.
• Option C (Hydrosphere): The hydrosphere (water bodies) has water ($H_2O$), but by volume, water is a small fraction of the hydrosphere’s total (and oxygen in water is not the dominant component of the hydrosphere’s volume overall).
• Option D (Crust): The Earth’s crust is composed of minerals like silicates (e.g., feldspar, quartz). Oxygen is a major component of these minerals; by volume, oxygen makes up about 49.5% of the crust, making it the most abundant element in the crust by volume.

Answer:

D. crust