Question 16 of 21: Question 6, Part 1: Multiple Choice

Question 6, Part 1: Multiple Choice (5 marks)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

1) → (d) erosion. Erosion is specifically the physical REMOVAL and transport of weathered material by an agent (wind, water, ice); it is distinct from weathering itself (the in-place breakdown).

2) → (b) Chemical weathering. Chemical weathering is the general term for mineral dissolution/decomposition via chemical reactions; hydrolysis (option c) is one SPECIFIC chemical-weathering reaction (not the general category), and mechanical weathering involves no compositional change.

3) → (d). Natural acidity accelerating weathering comes from CO₂ dissolved in rainwater/soil water (carbonic acid), organic acids released by decaying vegetation, industrially/volcanically-sourced acid rain, and sulphuric acid generated by the oxidation of sulphide minerals (notably pyrite) – not from plutonism, explosive eruptions, or Bowen's series (a crystallization-order concept, unrelated to acidity).

4) → (d). Mechanical (physical) weathering is driven by biologic activity (root wedging, burrowing), pressure-release expansion when overlying rock is eroded away (exfoliation/ unloading joints), and frost wedging (repeated freeze-thaw of water in cracks) – not by transport processes (which are erosion, not weathering) or vague unknowables.

5) → (a). The three classic chemical-weathering processes are dissolution (minerals go into solution), hydrolysis (water reacts with silicate minerals, e.g. feldspar → clay), and oxidation (electron transfer, e.g. Fe²⁺→Fe³⁺ producing rust- coloured iron oxides); the other option lists are either unrelated processes or a nonsense term ("dissimulation").