Oceanography and Hydrology

A billow is a large wave of water, or the rolling movement of something like smoke or clouds. Options A, B, and D refer to marriage status, providing qualities, and natural environments - none related to wave-like motion.

This is an analogy question testing relationship parallels. A desert contains an oasis (a fertile area within harsh conditions). Similarly, an ocean contains an island (land within water). The relationship is 'harsh environment : refuge/fertile spot within it'. Option B correctly maintains this analogy. Water and sea are components of ocean, not contained features like oasis/island.

The correct answer is 'near'. 'Turtles can sleep suspended near the surface of the water' correctly uses 'near' to indicate position in proximity to the water surface. Turtles can float or remain suspended just below or at the surface. 'Near' is the most precise preposition for this spatial relationship. Option A 'on' would imply touching the surface. Option C 'along' suggests movement or parallel positioning. Option D 'at' is less natural for describing proximity to a surface in this context.

"Near the surface" is the only logical choice for turtles sleeping while suspended in water. "On" would mean resting on top of the surface, which contradicts "suspended." "Along" and "at" don't convey the correct spatial relationship of being just below the water's surface.

The coastal areas show less contrast in temperature conditions due to the moderating effect of the seas.

Oceans absorb approximately 1/3 of CO₂ produced by humans, which has detrimental effects on marine environment. The increasing level of CO₂ in oceans changes the seawater chemistry by decreasing the level of pH. This process is also known as acidification.

Upwelling along desert coasts brings cold, nutrient-rich water from the deep ocean to the surface. These nutrients support phytoplankton growth, which creates a food chain that attracts large numbers of fish. This explains abundant fisheries off arid coasts like Peru, California, and West Africa.

The average salinity of seawater is approximately 3.5%, meaning about 35 grams of dissolved salts per kilogram of seawater. This value varies slightly by location (near river mouths vs. open ocean), but 3.5% is the standard accepted average.

Correct. We use 'just as' to compare verbs - 'causes tides' and 'sucking on a straw'. Also, the option removes the error of parallelism by narrating the cause and effect in the same sequence in both the examples.

According to Archimedes' principle, buoyant force equals weight of fluid displaced. Sea water has higher density than river water due to dissolved salts, so less volume needs to be displaced to balance the ship's weight.

The Sea of Tranquility (Mare Tranquillitatis) is a lunar mare on the Moon's surface. It was the landing site of Apollo 11, where Neil Armstrong and Buzz Aldrin became the first humans to land on the Moon on July 20, 1969.

An isthmmus is defined as a narrow strip of land connecting two larger land areas, typically separating two bodies of water. Classic examples include the Isthmus of Panama (connecting North and South America) and the Isthmus of Suez (connecting Africa and Asia). This geographical feature is significant for both natural ecosystems and human transportation routes like canals. Option B has a typo ('tow' instead of 'two') but is conceptually correct.

A geyser is a hot water spring that intermittently ejects a column of hot water and steam into the air. This occurs due to underground water being heated by magma, creating pressure that forces the water to erupt periodically.

A strait is a naturally formed, narrow, typically navigable waterway that connects two larger bodies of water. Examples include the Bering Strait (connects Arctic Ocean and Pacific Ocean), Strait of Gibraltar (connects Atlantic Ocean and Mediterranean Sea), and Palk Strait (connects Bay of Bengal and Palk Bay). An isthmus is a narrow strip of land connecting two larger land areas.

A river basin is the entire geographical area drained by a river and its tributaries. All water falling within this area eventually flows into the main river through its network of tributaries. Bay is a body of water partially enclosed by land, isthmus is a narrow strip of land connecting two larger areas, and strait is a narrow passage of water connecting two larger bodies.