(a) To what type of rock do each of specimens D, E, and F belong? (b) State the types of weathering caused by each of specimens G, H, and l (c) Give two way...

(a) Type of rock to which each specimen belongs

• Specimen D is an igneous rock.
• Specimen E is a sedimentary rock.
• Specimen F is an igneous rock.

(b) Type of weathering caused by each specimen

• Specimen G (earthworm) causes biological weathering (through its mechanical burrowing action).
• Specimen H (water) causes chemical weathering and physical (mechanical) weathering.
• Specimen I (ice block) causes physical (mechanical) weathering.

(c) Two ways by which each specimen causes weathering

• Specimen G (earthworm): it burrows into and widens cracks in the rock, breaking it into smaller particles; the burrows also admit water and air which further speed up rock disintegration.
• Specimen H (water): it dissolves soluble rock minerals and forms weak acids that chemically attack the rock; running water also drags rock particles which collide and wear against one another and the channel walls, breaking them down.
• Specimen I (ice block): when water in rock cracks freezes to ice it increases in volume, and the pressure exerted widens the cracks until the rock splits; the movement of ice along a path also dislodges and drags away rock particles.

(d) Three ways in which specimen D (igneous rock) is important to agriculture

• On weathering it breaks down to form soil, serving as the parent material of the soil.
• It releases and supplies mineral nutrients such as calcium and potassium to the soil.
• It is piled up to check erosion and is used to construct farm structures and access roads.