Consider the following critical minerals : I. Neodymium II. Tellurium III. Dysprosium IV. Gallium Which of the above minerals are not used for the production of photovoltaic cells used in solar panels?
- A.I and IV
- B.II and III
- C.I and III
- D.II and IV
Correct answer
Explanation
The correct answer is C, I and III. Neodymium and dysprosium are rare earth elements used mainly in strong permanent magnets, not in solar cells, while tellurium and gallium are used in photovoltaic cells.
Most solar panels use crystalline silicon, but thin-film and high-efficiency cells rely on other critical minerals. Cadmium telluride (CdTe) thin-film cells need tellurium. Gallium is used in copper indium gallium selenide (CIGS) thin films and in gallium arsenide cells, which power satellites because of their high efficiency. Neodymium, with a little dysprosium added to keep the magnet strong at high temperatures, goes into neodymium-iron-boron magnets used in wind turbine generators, electric vehicle motors, hard disks and speakers. All four are on India's list of critical minerals.
A is wrong because gallium (IV) is used in CIGS and gallium arsenide solar cells. B is wrong because tellurium (II) is the key element of cadmium telluride cells. D is wrong because both tellurium and gallium are photovoltaic minerals, the exact opposite of what is asked.
Exam tip: solar cells use silicon, tellurium, gallium, indium and selenium; magnets for wind turbines and EVs use neodymium and dysprosium.
Practice Questions
View allWhich of the following Ramsar Wetland sites is not situated in any of the Union Territories of India ?
- A.Hokera Wetland
- B.Point Calimere Wildlife and Bird Sanctuary
- C.Tsomoriri Lake
- D.Wular Lake
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Point Calimere, also called Kodiakkarai, lies in the Nagapattinam district of Tamil Nadu, a state, where the Coromandel Coast turns west towards Palk Strait.
Read the full explanation →In which one of the following groups of States in India is the Integrated Coastal Zone Management (ICZM) Project being implemented as a pilot investment?
- A.Gujarat, Kerala and Goa
- B.Kerala, Karnataka and Andhra Pradesh
- C.Gujarat, Odisha and West Bengal
- D.Maharashtra, Andhra Pradesh and Tamil Nadu
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The India Integrated Coastal Zone Management Project was launched by the Ministry of Environment and Forests in 2010 with World Bank support.
Read the full explanation →Which one of the following is a major environmental issue in eastern Canada ?
- A.Acid precipitation
- B.Groundwater depletion
- C.Land degradation
- D.Desertification
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Sulphur and nitrogen oxides from industries in the Great Lakes region and the US Midwest are carried by westerly winds and fall as acid rain and snow over eastern Canada.
Read the full explanation →Statement I : Global warming signifies the rise in global surface temperature. Statement II : The increase of concentration of greenhouse gases in the atmosphere causes the rise in global surface temperature.
- A.Both the statements are individually true and Statement II is the correct explanation of Statement I
- B.Both the statements are individually true but Statement II is not the correct explanation of Statement I
- C.Statement I is true but Statement II is false
- D.Statement I is false but Statement II is true
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Read the full explanation →Identify the land biome on the basis of the given characteristics : 1. Their climates are characterised by high rainfall and temperatures that vary from cold to mild. 2. These forests contain primarily deciduous trees - including maple, oak, hickory and beechwood. 3. Raccoons, opossums, bats and squirrels are found in the trees. Select the correct land biome from the options given below :
- A.Tropical forest
- B.Temperate forest
- C.Boreal forest
- D.Mediterranean forest
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