Which of the following types of coal contains higher percentage of volatile matter ?
UGC NET - 2012,
Answer: A
The volatile matter of a coal falls as its rank rises. Peat is the lowest rank and has the highest percentage of volatile matter, then lignite, bituminous coal and anthracite, which has the least. So peat is the answer.
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Which rare earth element is not present in the earth's crust but for commercial purpose comes from the Nuclear reactors ?
UGC NET - 2012,
Answer: A
Promethium has no stable isotopes, and it is not found in the earth's crust except in traces, so for commercial use it is obtained from nuclear reactors as a fission product. Lanthanum, cerium and samarium are present in the crust. The answer is promethium.
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Which one of the following is the most predominant element in a majority of igneous rocks ?
UGC NET - 2012,
Answer: C
Oxygen is the most abundant element in the earth's crust, and in igneous rocks it is combined in the silicates, so it is the predominant element, by number of atoms and by volume. Silicon and aluminium are next in abundance by weight, and iron comes after them. The answer is O.
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Which of the following type of materials present in a landslide suggest that the movement was rotational ?
UGC NET - 2013,
Answer: B
A rotational slide leaves rock slump, debris slump and earth slump material.
A slump is a rotational slide: the mass moves along a curved, concave-upward failure surface and tilts backwards as it moves. Flows are fluid-like movements, falls drop freely from a steep face, and topples rotate forward about a pivot point at the base. Each of those three is a different movement type, so they do not point to a rotational slide.
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A thermal power station has a heat rate of 12 mJ/kWh. Its thermal efficiency is
UGC NET - 2013,
Answer: A
A heat rate of 12 MJ/kWh gives a thermal efficiency of 30%.
One kilowatt-hour of electricity is 3.6 MJ, so efficiency is the useful output divided by the heat supplied per kWh.
\[ \eta = \dfrac{3.6}{12} \]
\[ = 0.30 = 30\% \]
The value 36% would result from a heat rate of 10 MJ/kWh, 40% from 9 MJ/kWh and 25% from 14.4 MJ/kWh, none of which is given.
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Assume that world coal production is 6.1 billion tons per year and estimated total recoverable resources of coal is 1.1 trillion tons. How long it would take to use up those reserves at current rate of production ?
UGC NET - 2013,
Answer: A
At the current rate the reserves would last about 180 years.
The time to exhaust a resource is the reserve divided by the annual production, with both in the same unit.
\[ t = \dfrac{1.1 \times 10^{12}}{6.1 \times 10^{9}} \]
\[ \approx 180 \text{ years} \]
The shorter times of 150, 120 and 90 years would need either a larger production rate or a smaller reserve than those stated.
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"Double digging" is a method of
UGC NET - 2013,
Answer: A
Double digging is a method of bio-intensive agriculture. The soil is loosened to a depth of about two spade lengths and compost is mixed in, which helps roots to grow deep and allows plants to be grown close together for high yields from a small area.
Deforestation is the clearing of forest, afforestation is the planting of trees where there were none, and water conservation uses other practices, so none of them is described by double digging.
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The volume of ejecta and the column height for a volcano are \(10^{8.5}\) m\(^{3}\) and 24 km, respectively. What is its volcanic explosivity index value ?
UGC NET - 2013,
Answer: D
The volcanic explosivity index is read from ejecta volume and plume height. An ejecta volume of \(10^{8.5}\) m\(^{3}\) is about 0.3 km\(^{3}\), which lies between \(10^{8}\) and \(10^{9}\) m\(^{3}\), and a column height of 24 km is in the 10 to 25 km range.
\[ 10^{8.5} \text{ m}^3 \approx 0.32 \text{ km}^3 \]
Both place the eruption at VEI 4, option D. VEI 2 is a much smaller eruption, and VEI 7 and 8 involve over 100 km\(^{3}\) of ejecta.
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In the context of material balance in hydrological cycle, which of the following equations is correct for oceans ?
UGC NET - 2013,
Answer: B
For the oceans the water balance is precipitation plus inflow (from rivers and runoff) equal to evaporation, when storage is taken as constant. So option B is correct.
Option A adds a change in storage to input, and C subtracts it, which is the general balance and not the equation for oceans in this question. Option D subtracts inflow, but inflow adds water to the ocean and so must be added.
Testing each of the remaining options against the same fact shows that every one of them fails on the point the question is asking about, which confirms the keyed answer.
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Which of the following material has the highest hydraulic conductivity ?
UGC NET - 2013,
Answer: B
Sandstone has the highest hydraulic conductivity of the four. Its interconnected pore spaces between sand grains let water pass freely, whereas clay has very small pores and low conductivity.
Quartzite is a tightly cemented metamorphic rock with very little primary porosity, and limestone is generally less conductive than sandstone unless it is heavily fractured or cavernous, so sandstone is the answer given in the key.
Testing each of the remaining options against the same fact shows that every one of them fails on the point the question is asking about, which confirms the keyed answer.
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