Question

of weathered bedrock. p. 165

1. ______________you can use the ph scale to measure how acidic a soil is. p.164

write the letter of the correct answer on the line at the left.

1. __ which soil layer contains little humus but much clay and other rock particles?

a a horizon
b b horizon
c c horizon
d bedrock
p.165

1. __ which process forms humus?

a weathering
b decomposition
c erosion
d freezing
p.166

1. __ what makes up soil besides rock particles, minerals, air, and water?

a carbonic acid
b acid rain
c oil
d decayed organic material
p.163

1. __ which soil is best for growing most plants?

a subsoil
b sandy soil
c loam
d clay
p.164

Explanation:

Question 7

The B horizon (subsoil) has little humus but accumulates clay and rock particles from the A horizon above. The A horizon has more humus, the C horizon is weathered bedrock with less clay accumulation, and bedrock is unweathered. So the correct answer is B.

Humus is formed from the decomposition of organic matter (like dead plants/animals). Weathering breaks rocks, erosion moves materials, and freezing is a physical process not related to humus formation. So decomposition (option B) forms humus.

Soil components include rock particles, minerals, air, water, and decayed organic material (humus). Carbonic acid, acid rain, and oil are not typical soil components. So the answer is D.

Answer:

B. B horizon

Question 8