Hydrological cycle

Correct answer: B. High temperature and dry air

Explanation: Correct answer: B, high temperature and dry air. Evaporation is the change of liquid water into water vapour. Heat gives water molecules more energy, so they escape from oceans, lakes, soil, and other wet surfaces more readily. Dry air can accept more water vapour than already humid air, so evaporation continues faster. A is wrong because low temperature supplies less energy, and calm air does not favour rapid removal of moist air. C is wrong because clouds reduce incoming sunlight and ice is difficult to evaporate. D is wrong because less sunlight reduces heating and humid air slows further evaporation. Memory cue: evaporation needs heat and air that is not already moisture-filled.

Correct answer: B. It moves slowly through underground layers

Explanation: Correct answer: B, groundwater moves slowly through underground layers. Rainwater may infiltrate the soil and percolate downward through pores and cracks. After entering an aquifer or another underground water-bearing layer, it generally travels slowly because the spaces are narrow and the material resists flow. Surface runoff is different: it moves over the land surface toward streams, rivers, lakes, or the sea. A describes surface runoff, not groundwater. C is wrong because clouds contain atmospheric water droplets or ice, not groundwater. D is wrong because an ocean wave is a movement of water at the sea surface caused by wind or other disturbances. Memory cue: runoff is visible on the surface; groundwater is hidden below it.

Correct answer: A. Because salts remain behind during evaporation

Explanation: Correct answer: A, salts remain behind during evaporation. Solar heating changes water at the ocean surface into water vapour, while dissolved salts do not normally enter the vapour with the water. The vapour rises, cools, and condenses into cloud droplets; precipitation from those droplets is therefore generally fresh, although it may collect small impurities from the atmosphere or surfaces. B is wrong because clouds do not chemically transform salt into water. C is wrong because seawater does contain dissolved salts. D is wrong because rivers are not responsible for removing salt during ocean evaporation. The key idea is separation during phase change: water moves upward as vapour, while most salts stay in the ocean. Memory cue: evaporation lifts water, not the dissolved salt.

Correct answer: B. Surface runoff

Explanation: Correct answer: B, surface runoff. Impermeable soil has very low permeability, so rainwater cannot easily enter its pores and move downward. When rainfall arrives faster than the ground can absorb it, the excess water travels across the surface toward lower land, drains, streams, and rivers. This is surface runoff. A is wrong because infiltration means water entering the soil, which decreases when the soil is highly impermeable. C is wrong because transpiration is water vapour released by plants and is not the direct result of reduced soil permeability. D is wrong because condensation is the change of water vapour into liquid droplets in the atmosphere. The exact amount of runoff also depends on rainfall intensity, slope, vegetation, and prior moisture, but impermeability favours runoff. Memory cue: blocked entry means more water stays on top.

Correct answer: A. Evaporation and cooling of air

Explanation: Correct answer: A, evaporation followed by cooling of air. First, solar energy changes water from oceans, lakes, soil, and vegetation into water vapour. The moist air rises or moves into a cooler region. As it cools, it may reach saturation, and water vapour condenses around tiny particles into microscopic droplets or ice crystals. A collection of these droplets or crystals forms a cloud. B is wrong because runoff and earthquakes are not the normal sequence for cloud formation. C concerns ocean-water properties and tides, not atmospheric condensation. D concerns water entering the ground and geological change, not clouds. Cooling is essential: evaporation alone adds vapour but does not by itself make a cloud. Memory cue: water vapour plus cooling leads to condensation and clouds.

Correct answer: A. Evaporation and transpiration

Explanation: Correct answer: A, evaporation and transpiration. Evaporation is the release of water vapour from non-living wet surfaces such as oceans, lakes, soil, and moist vegetation. Transpiration is the release of water vapour from plants, mainly through tiny openings in their leaves. Evapotranspiration combines these two upward transfers of water vapour from the land surface and vegetation to the atmosphere. B is wrong because precipitation is water falling from the atmosphere and glaciation involves ice formation, not the combined vapour loss. C is wrong because runoff is flowing water and tides are periodic sea-level movements. D is wrong because salinity is dissolved-salt concentration and erosion is the wearing away or transport of material. Memory cue: evapotranspiration = evaporation from surfaces + transpiration from plants.

Correct answer: A. River runoff

Explanation: Correct answer: A, river runoff. Rain and melting snow provide water to the land surface. Some water infiltrates the ground, some is stored temporarily, and some flows downhill into channels. Streams and rivers collect this surface and subsurface contribution and carry it toward lakes, estuaries, and finally the ocean. This return of water to the ocean completes an important part of the hydrological cycle, after which evaporation can begin again. B is wrong because condensation forms droplets or ice from water vapour in the atmosphere; it does not carry river water to the sea. C is wrong because transpiration sends plant water vapour into the atmosphere. D is wrong because ice-crystal formation is part of cloud or precipitation processes, not river-to-ocean transport. Memory cue: rivers are the visible return route from land to sea.

Correct answer: A. Ability of water to change state

Explanation: Direct answer: A, the ability of water to change state. The hydrological cycle describes the continuous movement of water between the atmosphere, land and oceans. Temperature controls whether water is solid ice or snow, liquid water in rivers, lakes and oceans, or gaseous water vapour. Heating can cause melting and evaporation, while cooling can cause condensation and freezing. These changes allow water to move from one reservoir to another without being destroyed. A is correct because it directly names this phase-changing property. B is wrong because rock age is a geological idea, not a water-cycle process. C is wrong because oceans do not disappear; water only moves and changes form. D is wrong because Earth’s rotation is unrelated to the meaning of phase change. Memory cue: heat changes ice to water and vapour; cooling reverses the process.

Correct answer: A. In soil, lakes, glaciers, and groundwater

Explanation: Direct answer: A, in soil, lakes, glaciers and groundwater. Rainwater does not all travel directly to the sea. Some infiltrates into soil and may recharge groundwater; some collects in lakes and wetlands; some is held as snow and ice in glaciers or seasonal snowfields. Vegetation can also temporarily intercept or store water, although that is not listed in the option. These stores delay runoff and give water different residence times before it returns to streams, rivers or oceans. A is correct because all four are genuine water reservoirs in the hydrological cycle. B is wrong because the Sun supplies energy but is not a water-storage reservoir. C is wrong because lava is not the normal storage location for rainwater. D is wrong because water vapour can enter the atmosphere, but rainwater storage in this question refers to Earth reservoirs. Memory cue: storage slows the journey from rain to river to ocean.

Correct answer: A. Time water stays in a reservoir

Explanation: Direct answer: A, the time water stays in a reservoir. In the hydrological cycle, a reservoir is a place where water is stored, such as an ocean, glacier, lake, soil layer, aquifer or the atmosphere. Residence time describes how long water remains there on average before leaving through evaporation, melting, runoff, groundwater flow, discharge or another transfer. The time is not identical for every individual water molecule, but the idea helps compare storage and movement. A is correct because it gives the simple definition. B is wrong because colour change is not a measure of time. C is wrong because residence time does not mean a particular ocean temperature. D is wrong because cloud size is a weather observation, not storage duration. Memory cue: residence means “staying”; residence time means how long water stays.

Correct answer: A. Oceans

Explanation: Direct answer: A, oceans. The oceans contain the largest share of Earth’s water and therefore form the largest major reservoir in the hydrological cycle. Their broad surfaces receive solar energy, causing evaporation that transfers water vapour to the atmosphere. Winds can move this moisture, and it may later condense and fall as precipitation over oceans or land. Ocean water is saline, so evaporation transfers mainly water vapour while most dissolved salts remain behind; this does not change the oceans’ role as the main moisture source. A is correct because it states both functions: storage and supply of atmospheric moisture. B is wrong because desert sand stores only limited water and is not the largest reservoir. C and D are wrong because volcanic ash and solid rocks are not the principal global water store or active moisture source. Memory cue: oceans are both the biggest store and the main evaporating surface.

Correct answer: A. Soil moisture, lakes, and groundwater

Explanation: Correct answer: A — soil moisture, lakes, and groundwater. A river basin does not send all received water immediately to the ocean. After rainfall, some water is held temporarily as moisture between soil particles, some collects in ponds and lakes, and some infiltrates and percolates downward to become groundwater. These are stores, or temporary reservoirs, in the hydrological cycle. Water may later leave them through evaporation, plant transpiration, springs, or river flow. Option A is correct because all three are real stores within a drainage basin. Option B is wrong because the Moon and stars are not water stores. Option C is wrong because lava and ash are volcanic materials, not normal basin stores. Option D is wrong because sea salt is a dissolved substance, not a store of freshwater in a river basin. Memory cue: rainfall can be stored in soil, surface water, or underground water before runoff reaches the sea.

Correct answer: A. Interconnection of Earth systems

Explanation: Correct answer: A — interconnection of Earth systems. The hydrological cycle links the hydrosphere, atmosphere, land surface, soil, and biosphere. Solar energy causes evaporation from oceans and land; water vapour moves through the atmosphere, condenses, and returns as precipitation. On land, water may run off, enter the soil, recharge groundwater, or be absorbed by plants. Plants return part of it through transpiration. Thus a change in one part can influence other parts, which is what interconnection means. Option A is correct because it describes the exchange among several Earth systems. Option B is too narrow: tides mainly describe periodic sea-level movement caused largely by gravitational forces, not the whole water cycle. Option C concerns a rock property and cannot explain evaporation or rainfall. Option D concerns astronomy and does not describe water exchange. Memory cue: the hydrological cycle is a connecting pathway, not an isolated ocean process.

Correct answer: B. Inter-system water transfer

Explanation: Correct answer: B — inter-system water transfer. The sequence begins when ocean water evaporates and enters the atmosphere as water vapour. Atmospheric transport carries that vapour, condensation forms clouds, and precipitation transfers water to the land surface. Therefore water has crossed from one Earth system or store to another: from the hydrosphere to the atmosphere and then back to land. Option B correctly describes this movement between connected components. Option A is wrong because soil formation is a slow process involving weathering, organic matter, and other factors; it is not the main process described. Option C is wrong because salinity is the concentration of dissolved salts, not the transfer of water. Option D is wrong because seismic activity involves earthquakes and tectonic movement. The wording “from ocean to atmosphere to land” is the clue. Memory cue: evaporation moves water upward, atmospheric transport moves it across space, and precipitation brings it to land.

Correct answer: C. Condensation

Explanation: Correct answer: C — condensation. Evaporation changes liquid water at the surface into water vapour. As moist air rises or meets cooler air, it may cool to the point at which vapour changes into tiny liquid droplets or ice crystals. This change is condensation, and the droplets gather to form clouds. When droplets or ice particles become large enough, they fall as precipitation, which may be rain. Option C is correct because condensation is the step between water vapour and cloud formation. Option A, runoff, happens when water flows over the land after precipitation; it is not an atmospheric step before rainfall. Option B, infiltration, is the entry of water into soil after it reaches the ground. Option D, salinity, means the amount of dissolved salt and is not a phase-change process. Memory cue: evaporation makes vapour; condensation makes clouds; precipitation makes rain or other forms of falling water.

Correct answer: A. Evaporation

Explanation: Correct answer: A — evaporation. Evaporation is the change of liquid water into water vapour from surfaces such as oceans, lakes, soil, and wet vegetation. High temperature supplies more energy to water molecules, so more of them can escape into the air. Dry air usually has less water vapour, so it can accept additional moisture more readily; this supports faster evaporation when water is available. Option A is therefore the best answer. Option B is wrong because glacier formation requires persistent cold conditions and accumulation of snow or ice, not high temperature. Option C is wrong because freezing requires temperatures at or below the relevant freezing point, not warmth. Option D is wrong because ocean-floor spreading is a tectonic process at divergent plate boundaries, unrelated to the immediate atmospheric water cycle. A dry place may still have little evaporation if no water is available, so the question says “may become faster.” Memory cue: heat provides energy and dry air increases the vapour-pressure difference.

Correct answer: A. Balance of input, output, and storage

Explanation: Direct answer: A is correct. A water budget is an accounting method for water in a particular area and period. First, identify inputs such as precipitation or water entering from elsewhere. Next, identify outputs such as evaporation, runoff, or water leaving the area. Finally, consider storage in soil, lakes, snow, groundwater, or other reservoirs. The basic relationship is input minus output equals change in storage. A is correct because it includes all three parts: received water, lost water, and stored water. B is wrong because rock, lava, and ash belong mainly to geological and volcanic processes, not water accounting. C is wrong because ocean colour is not a water-budget component. D is wrong because wind speed alone cannot describe water gained, lost, or stored. Memory cue: water budget means “water in, water out, water kept.”

Correct answer: B. Low precipitation and high evaporation

Explanation: Direct answer: B is correct. Drought is a prolonged condition of insufficient water availability. Step one is reduced input: low precipitation supplies less water to rivers, soil, lakes, and groundwater. Step two is increased loss: high evaporation removes water from land and surface stores, especially when heat or dryness persists. If this imbalance continues, soil moisture falls, recharge decreases, streamflow may decline, and water scarcity becomes more serious. B therefore describes a continuing water deficit. A is wrong because heavy rain and high recharge generally add water and reduce drought, although short-term flooding can still occur. C is not the best answer because low temperature and snow do not by themselves indicate a continuing water deficit; snow may store water. D is wrong because condensation and moisture generally support cloud formation and possible precipitation. Memory cue: drought means “less coming in, more going out.”

Correct answer: C. Heavy rain, saturated soil, and rapid runoff

Explanation: Direct answer: C is correct. Flooding occurs when water reaches the land or channel faster than the soil, drainage system, or river channel can absorb and carry it away. Heavy rainfall supplies a large amount of water in a short time. Saturated soil has little remaining capacity to accept infiltration, so more water remains at the surface. Rapid runoff then moves this excess water into streams and rivers, raising their level and possibly causing overflow. A is wrong because high infiltration and low runoff usually reduce surface-water accumulation. B is wrong because very little rainfall normally provides too little water for flooding, though local exceptions can occur. D is wrong because a decrease in ocean tide alone does not explain ordinary rainfall-runoff flooding. Memory cue: flood risk rises when rain is intense, soil is full, and runoff is fast.

Correct answer: B. Temporary storage of surface water

Explanation: Direct answer: B is correct. A lake receives and holds surface water for a period of time, so it acts as a temporary storage component of the hydrological cycle. Water may enter through rainfall, streams, or runoff and may later leave through evaporation, seepage, or an outlet stream. This storage slows the immediate movement of all water from land to rivers and oceans, although the exact residence time differs among lakes. A is wrong because a lake is not a permanent volcanic source; volcanic activity is a different process. C is wrong because lakes do not create the ocean floor. D is wrong because a lake is not merely a source of atmospheric dust; its main hydrological role is storing surface water. Memory cue: lakes are “temporary stops” in the journey of water.

Correct answer: A. Water storage

Explanation: Direct answer: A is correct. A river basin receives water and does not necessarily send every part of it immediately to the main river or ocean. Some water is temporarily held in soil moisture, lakes, wetlands, snow, or groundwater. This temporary holding is called basin storage. Step by step, precipitation or other input enters the basin, some water infiltrates or collects, and later part of it may return through runoff, springs, evaporation, or streamflow. A is correct because it describes water remaining within the basin for a period. B is wrong because an ocean tide is the regular rise and fall of sea level caused mainly by astronomical forces, not basin storage. C is wrong because plate tectonics concerns moving lithospheric plates. D is wrong because salt crystals are not the general concept for retained basin water. Memory cue: storage means water is present now but released later.

Correct answer: B. Both are opposite phase changes

Explanation: Direct answer: B is correct. Evaporation and condensation are opposite changes of state. In evaporation, heat allows liquid water at a surface to become water vapour, so the direction is liquid to gas. In condensation, water vapour cools and changes into liquid droplets, so the direction is gas to liquid. These processes connect surface water, the atmosphere, clouds, and precipitation in the hydrological cycle. A is wrong because the directions are not the same; one moves from liquid to gas and the other from gas to liquid. C is wrong because river flow describes movement of liquid water over land, not these phase changes. D is wrong because both processes are not restricted to groundwater; evaporation commonly occurs from exposed water and land, while condensation occurs in the atmosphere or on cool surfaces. Memory cue: evaporation goes up as vapour; condensation comes down as droplets.

Correct answer: B. Infiltration

Explanation: Answer: B, infiltration. Infiltration is the entry of water from the ground surface into the soil. Porous soil contains connected spaces through which water can pass. Gentle rainfall supplies water slowly, so the soil has time to absorb it instead of receiving more water than it can accept. After entering the soil, some water may remain as soil moisture and some may percolate deeper to recharge groundwater. A is less suitable because runoff occurs when water flows over the surface, especially when rainfall is intense or the ground is sealed, saturated, or steep. C is unrelated to the entry of water into soil; tides are regular rises and falls of sea level mainly associated with gravitational effects. D is a sound produced by lightning and is not a water-flow process. Memory cue: porous ground plus slow rain means more water goes in, so infiltration increases.

Correct answer: A. Rainwater being held on leaves and branches

Explanation: Answer: A, rainwater being held on leaves and branches. Interception is the temporary capture of precipitation by vegetation or other surfaces before the water reaches the ground. Leaves, branches, stems, and sometimes surface litter can hold part of the rainfall. Some intercepted water later evaporates directly back into the atmosphere; the rest may drip from leaves or flow down stems and then reach the soil. Thus vegetation changes the timing and pathway of water in the cycle. B is wrong because salt formation is a chemical or evaporative process, not the capture of rain by plants. C is wrong because groundwater cannot become an earthquake; earthquakes result from sudden movement and release of energy in Earth’s crust. D is wrong because interception does not describe river–ocean separation. Memory cue: interception means vegetation catches rain before it reaches the ground.

Correct answer: B. Plants to atmosphere

Explanation: Answer: B, from plants to the atmosphere. Plants absorb water from the soil through their roots. Much of this water is used in plant functions, and a large part eventually escapes as water vapour through tiny openings called stomata, mainly on leaves. This release of vapour from living plants is transpiration. Together, evaporation from surfaces and transpiration from plants are often considered evapotranspiration, an important return of water to the atmosphere. A is wrong because it describes neither the direct plant pathway nor transpiration. C is wrong because groundwater does not normally become lava; lava is molten rock. D is wrong because water falling from clouds onto land is precipitation, not transpiration. Memory cue: trans-piration means water vapour passes out through plant leaves.