Hydrological cycle

Correct answer: B. Water vapour absorbs some outgoing longwave radiation, contributing to the natural greenhouse effect. In the water cycle, it can condense into cloud droplets or form ice crystals when moist air cools and becomes saturated; clouds may then produce precipitation under suitable conditions. Unlike argon, water vapour is variable in amount.

Correct answer: A. Oceans cover a very large part of Earth’s surface, so evaporation from them is a major source of water vapour in the atmosphere. Solar energy changes some ocean water into vapour. Winds distribute this moisture, and cooling can cause condensation, cloud formation, and precipitation over oceans or land. Thus ocean evaporation supplies an important starting material for rainfall in many parts of the world. A is correct because it states the main connection between ocean evaporation and global rainfall. B is wrong because evaporation removes water but leaves most dissolved salts behind; it does not immediately turn the whole ocean into fresh water. C is wrong because ocean evaporation does not completely stop groundwater; groundwater is affected by infiltration, storage, extraction, and other processes. D is wrong because moisture from evaporation can help clouds form rather than remove them. Memory cue: ocean evaporation is the moisture source; winds transport it; cooling and condensation help produce rain.

Correct answer: B. Condensation is the change of water vapour into tiny liquid water droplets or ice crystals. Cooling is important because cool air can hold less water vapour than warm air. When air becomes saturated, it is holding as much water vapour as it can at that temperature. Further cooling or the presence of suitable condensation surfaces then allows excess vapour to condense, helping clouds form. B is correct because cool, saturated air provides the appropriate condition for effective condensation. A is wrong because dry air is far from saturation and hot air can generally hold more vapour. C is wrong because being below the ocean floor is not the atmospheric condition described in the water cycle. D is wrong because very hot lava promotes heating rather than the cooling needed for condensation. A useful sequence is: moist air cools, saturation is reached, condensation occurs, and clouds may form.

Correct answer: A. Transpiration is the release of water vapour from living plants, mainly through small openings in their leaves. Plants absorb water through their roots and move it to their stems and leaves; some of that water then enters the atmosphere as vapour. If vegetation decreases, there are fewer leaves and usually less plant water release, so transpiration may decrease directly. A is correct because it is the water-cycle process most immediately connected with plant cover. B is wrong because ocean tides are mainly related to gravitational effects and are not directly controlled by local vegetation. C is wrong because seismic vibration is caused by movements and energy within Earth, not by plant cover. D is wrong because ocean salinity concerns dissolved salts in seawater and is not the direct process described. Reduced vegetation can also change infiltration and runoff, but the direct plant-related process asked here is transpiration. Memory cue: transpiration is like evaporation through plants.

Correct answer: B. Groundwater recharge occurs when water infiltrates the ground and moves downward to replenish underground water stores. Runoff is water flowing over the land surface. If rainfall is rapidly carried away as runoff, less water may have time to enter the soil and percolate downward. Therefore, high runoff can reduce groundwater recharge, especially when the ground is compacted, steep, or already saturated. B is correct because it says recharge may decrease, not that it must always decrease; actual results depend on soil, slope, vegetation, rainfall intensity, and land cover. A is wrong because groundwater cannot become infinite. C is wrong because runoff does not become an ocean tide; a tide is a periodic sea-level movement. D is wrong because runoff does not stop atmospheric condensation. Remember the basic contrast: infiltration sends water into the ground, while runoff carries water across the surface. More surface flow can mean less opportunity for infiltration.

Correct answer: A. After ocean water evaporates, the resulting water vapour is present in the atmosphere. Winds move air masses, so they can transport moist air from oceanic regions towards land. When this air rises, cools, and becomes saturated, condensation and cloud formation may occur, followed by precipitation. A is correct because winds provide the atmospheric movement that carries moisture over large distances. B is wrong because the age of rocks does not transport water vapour. C is wrong because Earth’s core is deep inside the planet and is not the agent that carries atmospheric moisture. D is wrong because the colour of sea salt has no role in moving water vapour. The amount and direction of moisture transport also depend on atmospheric circulation, but among these options, winds are the direct factor. Memory cue: evaporation supplies moisture, winds transport it, and cooling helps turn it into precipitation.

Correct answer: A. After precipitation reaches the ground, part of the water flows downhill over the land surface. This movement is called surface runoff. Small streams may join larger streams and rivers, so runoff can supply water directly to river channels and increase river discharge. Another part of precipitation may infiltrate into the soil and later reach rivers as groundwater flow, but that is not the option given. A is correct because it names a real post-precipitation pathway from land to rivers. B is wrong because solar radiation is energy from the Sun, not a pathway carrying water. C is wrong because a seismic wave is a movement of energy through Earth materials. D is wrong because ocean salinity describes dissolved salts in seawater and does not transport rainfall to rivers. Runoff is usually greater when rainfall is intense, slopes are steep, soil is impermeable, or vegetation is limited. Memory cue: precipitation on the surface can run off into streams and rivers.

Glaciers are large, long-lasting stores of fresh water. They hold water in solid form as snow and ice, often for many years or centuries. In this way, they are an important part of the hydrological cycle because they temporarily keep water out of rivers, lakes, oceans, and the atmosphere. They also provide meltwater when temperatures rise.

Therefore, option A is correct: glaciers store water as ice for long periods. The other choices describe impossible effects. Glaciers do not immediately empty oceans, turn clouds into soil, or completely stop evaporation. Their main role is delayed storage and gradual release of water, especially during seasonal melting. This makes the idea of a glacier similar to a natural frozen reservoir.

Correct answer: B, groundwater storage. Percolation is the downward movement of water through soil and porous or fractured rock under gravity. If the water reaches a saturated underground layer, it can add to an aquifer and increase groundwater storage, provided recharge is greater than groundwater withdrawal and discharge. A is wrong because ocean waves are surface movements and are not a storage created by percolation. C is not a water store and does not increase through underground movement. D is wrong because percolating water does not directly create sea salt; salt concentration depends on dissolved minerals and water balance. Groundwater may later emerge through springs, feed rivers, or be pumped, linking this store to other parts of the cycle. Memory cue: percolation means water goes down and recharges underground storage.

Correct answer: A. Solar energy supplies the heat needed for evaporation from oceans, lakes, soil, and plants. It also helps drive the movement of water vapour through the atmosphere. Gravity then pulls condensed water downward as precipitation and moves water over land as runoff, into soil by infiltration, and through underground layers. Together, energy from the Sun and gravity keep water circulating between the surface, atmosphere, and subsurface. B is wrong because neither has the sole role of increasing salinity. C is wrong because earthquakes are caused by geological processes, not the combined normal action described here. D is wrong because clouds are temporary and change through condensation and precipitation. The roles are complementary: solar energy mainly drives upward movement and gravity drives downward and downhill movement. Memory cue: the Sun lifts water; gravity brings and guides it back.

Correct answer: A, surface runoff. Saturated soil has already filled most of its available pore spaces with water, so its capacity to accept additional rainfall is very small. If precipitation is also intense, water arrives faster than it can infiltrate. The excess therefore flows across the ground surface, increasing runoff and possibly stream discharge or flood risk. B is wrong because condensation is the atmospheric change from vapour to liquid or ice and is not the direct response described. C is wrong because intense rain over saturated soil does not directly increase ocean evaporation. D is wrong because rainfall does not make ocean salinity become zero. Runoff can be reduced by vegetation, permeable soil, and gentle slopes, but saturated ground strongly favours it. Memory cue: full soil plus fast rain means water must run over the surface.

The correct answer is A. A mountain can force moist air to rise. As the air rises, it expands and cools; water vapour may then condense into cloud droplets or ice crystals. If these grow large enough, precipitation falls as rain or snow, depending on temperature. This is the orographic effect.

The correct answer is A. Steep slopes help water flow downhill more quickly, while heavy rainfall can supply water faster than the ground can absorb it. This can increase surface runoff and cause stream and river flow to rise more rapidly.

Correct answer: A, porous soil. Infiltration means the downward entry of water from the ground surface into the soil. Soil containing many connected pores provides small spaces through which water can move downward and may later contribute to groundwater. The rate also depends on rainfall intensity, vegetation, slope, and soil condition, but among these choices porous soil is clearly infiltration-friendly. A is correct because its open pores allow water to enter. B is wrong because concrete is a hard, nearly impermeable surface and usually produces surface runoff. C is wrong because a very steep slope gives water less time to remain on the ground, so runoff commonly increases and infiltration decreases. D is wrong because impermeable rock does not readily allow water to pass through it. Memory cue: pores promote penetration; paving and steep slopes promote runoff.

Correct answer: A, when cloud droplets become large enough to fall by gravity. Clouds contain tiny water droplets or ice particles suspended in air. They can grow when droplets collide and join, or when water vapour deposits on ice crystals in suitable cold clouds. As particles become larger and heavier, air currents can no longer keep them suspended. They then fall as rain, snow, sleet, or another form of precipitation, depending on atmospheric temperature. A is correct because sufficient size and weight are necessary for falling precipitation. B is wrong because an empty cloud cannot produce precipitation. C is wrong because oceans supply much water through evaporation; they do not need to be waterless. D is wrong because moisture is essential for cloud formation and precipitation. Memory cue: cloud formation stores water; particle growth releases it as precipitation.

Correct answer: A, snowmelt and groundwater flow. A river receives water through several pathways in the hydrological cycle. Rainfall may flow directly over the land into channels, while melting snow and glaciers can supply water, especially in colder or high mountainous regions. Some rainfall also infiltrates the ground and moves slowly as groundwater; this subsurface flow can feed springs and rivers. A is correct because both snowmelt and groundwater are genuine water sources. B is wrong because the colour of sea salt does not add water to a river. C is wrong because the shine of rocks is unrelated to water supply. D is wrong because the sound of an earthquake is not a hydrological input. The amount supplied by each source varies with season, climate, relief, and geology. Memory cue: rivers may receive rain from above, meltwater from high ground, and groundwater from below.

Correct answer: A. Ocean level depends partly on the balance between water entering and leaving the oceans. Precipitation adds water directly, and rivers carry water from land to the sea. Melting land ice can add freshwater to the oceans, while evaporation removes water from their surface and transfers it to the atmosphere. Over longer periods, storage in ice, groundwater, and other parts of the cycle can also influence the balance. A is correct because it lists several real hydrological inputs and outputs. B is wrong because cloud colour does not itself add or remove water. C is wrong because desert dust alone is not the controlling water-balance factor. D is wrong because rock texture is not, by itself, a direct ocean-level process. The wording says “can be affected,” so it does not claim that all factors act with equal strength at every moment. Memory cue: ocean level reflects water in minus water out.

Correct answer: A, precipitation and runoff. In the land phase of the hydrological cycle, water vapour in the atmosphere condenses and returns to Earth as precipitation. After reaching land, part of the water infiltrates, part may be stored, and part flows over the surface through streams and rivers. This surface runoff eventually carries water back to lakes, rivers, and oceans; groundwater flow can also contribute to the return. A is correct because precipitation represents the movement from atmosphere to land and runoff represents an important return route to the ocean. B is wrong because tides and salinity describe ocean-water conditions or movements, not this complete land link. C is wrong because earthquakes and weathering are not the two necessary transport stages. D is wrong because transpiration sends water vapour to the atmosphere, while lava is molten rock, not water. Memory cue: precipitation comes down; runoff carries water onward.

Correct answer: A, low precipitation for a long time. Drought is a prolonged period in which available water is insufficient for the usual needs of people, ecosystems, agriculture, or other activities. A sustained shortage of precipitation reduces soil moisture, streamflow, groundwater recharge, and stored water, although evaporation, temperature, land use, and water demand can also affect drought severity. A is correct because persistent low precipitation is a common meteorological cause of water shortage. B is wrong because earthquakes do not define a precipitation deficit. C is wrong because a change in salt colour is not a measure of water availability. D is wrong because rock hardness is not the direct meaning or necessary cause of drought. A single dry day is not automatically a drought; duration and effects matter. Memory cue: drought means too little usable water for too long, commonly after deficient precipitation.

Correct answer: A, during heavy rainfall and low infiltration. Flooding occurs when water reaches a place faster than it can infiltrate, be stored, or flow safely through channels. Heavy rainfall supplies a large volume of water in a short time. If the soil is saturated, compacted, paved, frozen, or otherwise poorly permeable, little water enters the ground and more becomes surface runoff. That runoff can rapidly raise stream and river levels. A is correct because it combines a large water input with a limited pathway into the soil. B is generally wrong because light rainfall and high infiltration usually reduce immediate surface runoff, though local conditions can vary. C is wrong because moistureless air does not provide the heavy water input described. D is wrong because the absence of sea waves does not determine rainfall runoff or river flooding. Memory cue: intense rain plus blocked entry equals more runoff and greater flood risk.

Correct answer: A, because atmospheric circulation can carry moisture far away. Solar heating causes evaporation from ocean surfaces, changing liquid water into water vapour. That vapour is transported by winds and larger atmospheric circulation, so it may move over distant ocean areas or continents before condensing and falling as precipitation. Therefore, oceanic evaporation participates in the global transfer of water rather than affecting only the small area above the source ocean. A is correct because transport spreads moisture across regions. B is wrong because water vapour leaves the ocean and enters the atmosphere. C is wrong because precipitation also occurs over land. D is wrong because winds are a major means of moving atmospheric moisture. Evaporation and rainfall are not necessarily at the same place or time. Memory cue: evaporation starts locally, but atmospheric transport makes its effects global.

Correct answer: A, both can transfer land water onward. Rivers are visible surface pathways that carry water downhill through channels toward lakes, wetlands, and eventually the sea. Groundwater moves through pores and cracks below the surface, often slowly, and may emerge in springs or feed streams and rivers. Both therefore help redistribute water across the land and connect storage areas in the hydrological cycle, although their speeds and routes differ. A is correct because it states their shared function without claiming that they move water in the same way. B is wrong because clouds contain atmospheric water, whereas rivers and groundwater are surface and subsurface stores. C is wrong because neither is defined by producing sea salt. D is wrong because neither stops solar heating. Memory cue: rivers are surface routes; groundwater is a subsurface route, but both transport water.

Correct answer: A, transpiration. Plants absorb water from the soil through their roots and transport it through their tissues. Most of the absorbed water is not permanently stored; it can leave the plant as water vapour through very small openings called stomata, especially in leaves. This release of water vapour to the atmosphere is transpiration, an important part of the hydrological cycle. A is correct because it specifically describes atmospheric water loss from plants. B is wrong because salinity means the concentration of dissolved salts, not the release of plant water. C is wrong because an ocean current is the movement of seawater. D is wrong because a seismic wave is an earthquake-related wave, not a water-transfer process. Evaporation from soil and open water may occur at the same time, but water released through plant leaves is called transpiration. Memory cue: plants perspire through leaves—transpiration returns water vapour to the air.

Correct answer: A, a surface water reservoir. The hydrological cycle describes the continuous movement of water between the atmosphere, land and water bodies. Water does not always move immediately; it may remain stored for some time in lakes, ponds, rivers, glaciers, soil or groundwater. A lake holds water on the land surface, so it is a surface reservoir. Later, some of this water may evaporate, seep into the ground, flow into a river or be used by plants. B is wrong because an earthquake source is related to tectonic activity, not stored lake water. C is wrong because a lake is not being described as a sea-salt source. D is wrong because lava is molten rock from volcanic activity. Memory cue: a reservoir stores water; it does not create earthquakes or lava.

Correct answer: A. Infiltration means water entering the soil, while runoff means water flowing over the land surface. During urbanisation, roads, roofs, pavements and concrete cover much of the ground. These surfaces are relatively impervious, so rainwater cannot easily enter the soil. Therefore infiltration usually decreases and surface runoff increases. More rapid runoff can contribute to waterlogging or urban flooding, while reduced infiltration can limit the natural recharge of groundwater. B is wrong because urbanisation cannot make groundwater infinite; excessive pumping may even lower it. C is wrong because clouds can still form over cities through evaporation, cooling and condensation. D is wrong because urbanisation does not immediately remove ocean water. Memory cue: concrete blocks entry, so water runs away.