Chapter 1 – Answer Key A. MCQs (b) Crest (c) Moon (d) Deep sea floor (c) Petroleum (c) Waves (b) Mid-ocean ridges (c) Decline in fish stocks (c) Tide (d) Sea routes (c) Rising sea temperatures (c) Both II and III I is incorrect because waves mainly help in mixing ocean water, not specifically by distributing heat and nutrients. II and III are correct. 12. Match the following A. Crest → IV. The highest point of a wave B. Trough → III. The lowest point between two waves C. Wavelength → II. The distance between two successive crests or troughs D. Wave height → I. The vertical distance between crest and trough Answer: (b) A-IV, B-III, C-II, D-I 13. Statement-based question Answer: (a) Both statements are correct. B. Fill in the Blanks Seamounts are large elevated areas on the ocean floor, often formed by extensive volcanic eruptions. Abyssal plains are vast, flat areas of the deep ocean floor found at depths between 3,000 and 6,000 metres. The ocean floor is generally divided into th...