Question

1. according to the earth science references tables, the element oxygen is found in the earths

a) troposphere and hydrosphere, only
b) troposphere, hydrosphere, and crust
c) troposphere, only
d) hvdmsnhem only

Explanation:

To solve this, we recall Earth's spheres and oxygen distribution:

• Troposphere (lower atmosphere) has gaseous oxygen ($\ce{O2}$).
• Hydrosphere (water bodies) has oxygen in $\ce{H2O}$ (water) and dissolved $\ce{O2}$.
• Crust (Earth’s outer solid layer) has oxygen in minerals (e.g., silicates, oxides).

Option A is wrong (oxygen is in crust too). Option C is wrong (not only troposphere). Option D is incomplete. Option B includes all three spheres where oxygen is found.

Answer:

B. troposphere, hydrosphere, and crust