CSIR NET Earth Science Mock Test - 2 - CSIR NET Earth Science MCQ

Blue light wavelengths of visible spectrum penetrate deepest in the oceanic euphoric layer.

The minimum absorption, and therefore the greatest penetration is around λ =420nm, which is on the boundary between blue and violet light. The intensity of sunlight peaks between λ =500λ =500 and 550550nm and it falls rapidly at smaller wavelengths.

So even though water absorbs least at violet wavelengths the light intensity decreases because there isn’t that much violet light in sunlight.

The maximum penetration at around λ = 475λ =475nm is a tradeoff between the decreased absorption and decreased intensity as the wavelength decreases.

Quaternary period is during the most recent ice-ages. During this period, Continental glaciers advanced equatorward and alpine glaciers advance downslope which resulted as large scale scouring and erosion.

This theory explains the mode and cause of the earthquakes. The Elastic Rebound Theory is given by Harry Fielding Reid. This theory was one of the first satisfactory theory related to earthquakes.

The place of the occurrence of an earthquake or the source point is called as focus. Faults denote weaker zones in the Earth's crust. Epicentre is the place where the seismic event is first experienced.

The non-metallic minerals have low values of density, ranging between 2.5 and 4.5 g/cc, whereas metallic minerals and ores have densities as high as 20 g/cc.

The ocean seaways/gateways play a critical role in the evolution of global ocean circulation, climate, and marine biota. Central America volcanic arc and South America collided in Miocene, resulted closing of Bering Strait and panama isthmus. The results of closing of panama isthmus were, climate change leading to the waxing and waning of ice sheets on Northern Hemisphere, changed in ocean and atmosphere circulation and global climate change.

Sediment sorting is the degree of dispersion of a grain-size distribution around a central value (mean, median, or mode). The measurement of the degree of sorting of a grain-size distribution is calculated by any of the statistical dispersion measurements. Among them, the standard deviation is the most common.

Sorting reflects both sediment source and transport. Aeolian-transported sediments are the best sorted and glacial sediments is the poorest sorted.

Saprolite is a chemically weathered rock that form in the lower zones of the soil profiles.

It represents deep weathering of the bedrock surface. The colour of saprolites comes from the ferric compounds available in the most of the outcrops.

Deeply weathered profiles are extensively found on the continental landmasses between 35^oN latitudes and 35^oS.

Matrix flow is the throughflow pathway in which the water travel through the finest soil pores.

It is a relative slow and even movement of water that solutes through the soil while sampling all the pore spaces.

It obeys the convective-dispersion theory, which assumes that the water follows an average flow path through the soil.

Komatite

Eclogite

Nepheline Syenite

Phosphorite

Komatite is an ancient ultramafic volcanic rock.

Nepheline Syenite is silica under saturated plutonic rock with nepheline replacing orthoclase.

The lower most layer of the atmosphere is troposphere. It ranges in thickness from 8Km at the poles to 16Km over the equator. The troposphere is bounded above by the tropopause.

Above the troposphere is the stratosphere. Temperature usually declines with increasing altitude in the troposphere. The troposphere is denser than the layers of the atmosphere above it because of the weight compressing it. It contains 75% total gaseous mass of the atmosphere.

It is primarily composed of nitrogen 78% and oxygen 21% with only small concentrations of other trace gases. Nearly all atmospheric water vapour or moisture is found in the troposphere.

River training works are classified into three types:

Low water training for rivers is also known as training for depth. It is trained for providing sufficient depth for navigation during the low stage of a river.

High water training for rivers is also known as training for discharge. It is trained for providing sufficient and efficient C/S area for the expeditious passage of maximum flood.

Mean water training for rivers is also known as training for sediment. The river is trained to correct the configuration of the river bed for efficient transport and it also keeps the channel in a good shape.

The thunderstorm begins to dissipate when the downdrafts in the cloud begins to dominate over the updraft.

Since the warm moist air can no longer rise, the cloud droplets can no longer form.

The storm dies out with light rain as the cloud disappears from the bottom to the top.

The whole process takes about one hour for an ordinary thunderstorm to complete. The supercell thunderstorms are much larger, more powerful, and last for several hours.

As the temperature decreases, its volume decreases, and density increases. As the surface water reaches about 4℃, it becomes denser and sinks to the bottom allowing the less dense water to surface up. As temperature falls below 4℃, surface water becomes lighter (less dense) compared to the water below and floats until it freezes. Once frozen, the ice insulates the water at the bottom from cooling so its temperature is maintained between 0 and almost 4℃, keeping it from freezing.

The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about -2℃ 28℉.

.So, ice form more easily in low salinity and shallow water.

Along the west coast of India, there is an increase in width of continental shelf south to north as the figure below.

Tidal amplitude increases with an increase in continental shelf. Tidal range is low in the south along the west coast of India and it increases towards north.

The tides are found to be mixed semidiurnal type in the southern part of the shelf and become more semidiurnal type further north.

Velocity is in all areas of a river channel. Velocity varies vertically and laterally across the river.

In a straight river channel, velocity is always greatest in the middle away from the banks and bed of the channel.

In deeper places, the flow is faster while in shallower places the flow is slower because there is more surface contact and friction in shallower places.

Average flow velocity at a cross section occurs at 0.6 depth. Velocity is higher over steeper gradients.

Coarse-grained rocks are usually more permeable than fine-grained rocks, and sands are more permeable than clays.

Well-rounded coarse-grained sediments usually have higher porosity than fine-grained sediments, because the grains do not fit together well.

A drumlin is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacial ice acting on underlying unconsolidated till or ground moraine.

A roche moutonnee is a rock hill shaped by the passage of ice to give a smooth up-ice side & rough, plucked and cliff-girt surface on the down-ice side. Upstream surface is marked with striations. They are aligned roughly parallel to ice flow.

Cumulus clouds are fair-weather clouds but as they get big enough to produce thunderstorms, they are called cumulonimbus. Cumulonimbus clouds are formed by upwelling plumes of hot air that produce turbulence on their upper surfaces. When it takes heat to evaporate water from Earth’s surface, heat is released.

It then condenses to form clouds. In thunderheads, this energy is capable to produce hail, damage winds, lightning, torrential rain, and sometimes tornadoes.

When thunderheads reach high elevations, their tops encounter high winds leading to “anvil tops. “

Pre-Holocene events that coincided with the destruction of nor them hemisphere ice shelves and release of large volume of sea ice, icebergs and fresh water into the oceans are known as Heinrich events. It is a natural phenomenon. They occurred during five of the last 7 ice ages. This was 1st discovered by Hartmut Heinrich.

Coral reef ecosystems are oases of life in the oceans, because of their ability to support a lot of biodiversity. They are as productive as tropical rainforests. Akm² of a healthy coral reef can yield an average of 15 tons of fish and other seafood per year. Mollusks, marine turtles, sea horses, starfish and sea urchins are formed more in coral areas.

A river valley is the result of down-cutting and bank erosion by the river. Since most of the river erosion processes are concentrated along the bottom of a river channel, especially in the mountainous regions, the resulting river valley has a typical V-shaped cross-section.

Albedo is defined as the ratio of reflected solar radiation to total received solar radiation.

Object which has the largest reflection has highest albedo. Vegetation has the lowest albedo since it absorbs maximum amount of solar radiation.

A western disturbance is an extra-tropical storm that originates in the Mediterranean region. It brings sudden winter rain to the north-western part of the Indian sub-continent. It refers to a non-monsoonal precipitation pattern, which is driven by the Westerlies.

The moisture driving these storms generally originates over the Mediterranean Sea and the Atlantic Ocean. In extra-tropical storms, the moisture usually carried in the upper atmosphere, unlike their tropical counterparts where the moisture is carried in the lower atmosphere.

In the case of the Indian subcontinent, this moisture is occasionally shed as rain when the storm system encounters the Himalayas. The western disturbances are important for the development of the Rabi crop, such as wheat.

Madhya Pradesh is the only state in India as well as in Asia with a diamond mine.

The state has produced 28,424 carats of diamonds during the year 2017 - 18. The Majhgawan mine at Panna is the only source of diamonds in Asia producing 30,000 carats every year.

This mine is located in the Panna district of Madhya Pradesh state, which spreads over an area of 80 km starting from the Paharikhera North-East and ending in the Majhgawan South-West having a width of about 30 km.

Stones like all other solids fail when subjected to loads beyond their strength. The failure takes place under compressive, tensile and shear forces at different values. It is however, the unconfined compressive strength, which is taken as the most important index property of stones.