Answers to CE MC Questions (1992-2000)

ROCKS

Question	Ans.	Explanation
9508	B	The diagram shows two characteristics of granite: coarse-grained and acidic (= high silica content).
9304	B	The diagram shows rhyolite which is formed by the cooling of lava.
9807	C	Metamorphic rocks are found near intrusion of magma where temperature is high so as to alternate the composition and structure and rocks. This is called thermal metamorphism.
9919	B	The similar diagram as 9304.
9306	A	Granite is exposed to the earth surface by weathering and erosion.
9512	B	The photo shows shale found in Mirs Bay, Peng Chau. Shale is a mechanically-formed sedimentary rock which is made up of fine silt.
9205	A	Only sedimentary rocks are fossil-bearing.
9812	B	Conglomerate is made up of rounded pebbles.
0014	D	The angular fragments show that the rock should be breccia.
0017	C	The layered structure shows that it is a kind of sedimentary rock. No evidence of magma intrusion can be found.
9717	C	Coarser materials, like rock fragments, are deposited near the coast while finer materials, like silt, are brought far away from the coast.
9918	D	Marble is an example of metamorphic rock while sandstone is sedimentary rock.
9813	D	Metamorphic rocks are formed when there is high temperature or pressure. All except (1) can satisfy the above requirements.
9608	B	The shaded areas show the granitic regions of Hong Kong. Granite is a plutonic rock which is acidic and well-jointed with light colour.
9206	A	Limestone and gypsum are examples of chemically-formed sedimentary rocks while coal is an example of organically-formed sedimentary rocks.
9718	B	Intrusion of magma means there is intrusive igneous activities. They lead to the formation of hypabyysal rocks and plutonic rocks. The heat underground may also alter the mineral composition and rock structure and form metamorphic rocks. It does not lead to the formation of volcanic as the magma doesn’t come out to the surface to form lava.
0023	B	Volcanic rocks like rhyolite are found in the eastern part of Sai Kung Peninsula. Sedimentary rocks like conglomerate and shale can be found in Pat Sin Range and Bride’s Pool area.
9618	A	The photo shows rhyolite found in a dry river bed. The hexagonal columnar joints are one of the characteristics of rhyolite. They are formed due to rapid cooling of lava. So, they are NOT formed by weathering and erosion.
9404	D
9410	B	Most of the sedimentary rocks are found in the northeastern part of the New Territories.
9713	D	(1) is irrelevant to the question.
0019	D	This item was deleted in exam. The photo is actually showing the famous tourist spot in Blue Mountain, Australia, Three Sisters.
9305	B	A fault line is clearly seen in (1). The smooth surface of the pebbles is produced by abrasion. The depression hollows left on the rock surface are produced by honey-comb weathering. They are usually caused by salt spray from the sea. In (4), the diagram shows signs of physical weathering which is found in dry areas.
9821	C	The resistance of rock cannot affect the growth of vegetation.