Chemistry (Part-II) (UPSC)

Total Questions: 56

51. With reference to two non-conventional energy sources called 'coalbed methane' and 'shale gas', consider the following statements: [ [2014-I]

1. Coalbed methane is the pure methane gas extracted from coal seams, while shale gas is a mixture of propane and butane only that can be extracted from fine-grained sedimentary rocks.
2. In India, abundant coalbed methane sources exist, but so far no shale gas sources have been found.

Which of the statements given above is/are correct?

Correct Answer: (d) Neither 1 nor 2
Solution:Shale gas contains methane, according to first statement, it contains propane and butane which is wrong. The source of shale gas is available in India. So the statement (2) is also wrong.

Following are the places where shale gas is found in India:

  • Cambay, Gondwana, Krishna-Godawari on land, and Cauvery.
  • Public sector companies and corporations like ONGC, OIL and GAIL are exploring these sites.
  • Subject matter falls under Director General of Hydro carbans (DGH).
  • MoU have been signed between USA, and India for sharing technical knowledge in shale-gas exploration. This is one area where USA is far ahead of us, we've much to learn from them.

52. Consider the following pairs: [2017-I]

Commonly used consumed materials Unwanted or controversial chemicals likely to be found in them

1. Lipstick: Lead
2. Soft drinks: Brominated vegetable oils
3. Chinese fast food: Monosodium glutamate

Which of the pairs given above is/are correctly matched?

Correct Answer: (d) 1, 2 and 3
Solution:Monosodium Glutamate (MSG) is a flavor enhancer in Chinese food, but leads to obesity and liver inflation. This was in news because of Maggie noodles controvery. So, 3 is right.
  • Brominated vegetable oils are used as stabilizers in the baked goods, soft drinks, soups, jellies etc. but banned in UK after 1970. So, #2 is right.

There is only one combination where 1 and 3 are together i.e. answer "D": 1, 2 and 3 are correct.

53. In the context of which one of the following are the terms pyrolysis and plasma gasification mentioned? [2019-1]

Correct Answer: (d) Waste to energy technologies
Solution:
  • Pyrolysis is a process of combustion in absence of oxygen or the material burnt under controlled atmosphere of oxygen. It is an alternative to incineration. The gas and liquid thus obtained can be used as fuels.
  • Pyrolysis is the thermal decomposition of materials at elevated temperatures in an inert atmosphere.
  • In general, pyrolysis of organic substances produces volatile products and leaves a solid residue enriched in carbon, char.
  • Pyrolysis is not effective in either destroying or physically separating inorganics from the contaminated medium.

54. In India, the use of carbofuran, methyl parathion phorate and triazophos is viewed with apprehension. These chemicals are used as [2019-I]

Correct Answer: (a) pesticides in agriculture
Solution:The Ministry of Agriculture has issued a notification inviting objections and suggestions from the stakeholders on completely banning pesticides/insecticides including Benomyl, Carbaryl, Diazinon, Fenarimol, Fenthion, Linuron, MEMC, Methyl Parthion, Sodium Cyanide, Thiometon, Tridemorph, Trifluralin, Alachlor, Dichlorvos, Phorate, Phosphamidon, Triazophos and Trichlorfon. So, A is the right answer.

55. With reference to radioi-sotope thermoelectric generators (RTGS), consider the following statements : [2024-I]

1. RTGs are miniature fission reactors.
2. RTGs are used for powering the onboard systems of spacecrafts.
3. RTGs can use Plutonium-238, which is a by-product of weapons development.

Which of the statements given above are correct?

Correct Answer: (b) 2 and 3 only
Solution:Radioisotope thermoelectric generators (RTGS) harness heat from the natural decay of plutonium-238 to produce electricity via thermocouples. Unlike nuclear reactors, they do not rely on controlled fission reactions.

RTGs are essential for spacecraft and remote installations where solar power is not viable, enduring harsh environments for decades with minimal maintenance. They have powered over two dozen U.S. space missions since 1961, providing reliable, long-term energy solutions.

Plutonium-238, a by product of nuclear weapons development, serves as the fuel source for RTGs, steadily emitting heat that thermocouples convert into electrical power. This technology plays a crucial role in deep space exploration and missions where consistent, durable power sources are essential. Thus, statement 1 is incorrect. Hence the correct answer is (b).

56. Consider the following: [2024-I]

1. Battery storage
2. Biomass generators
3. Fuel cells
4. Rooftop solar photovoltaic units

How many of the above are considered "Distributed Energy Resources"?

Correct Answer: (d) All four
Solution:Distributed Energy Resources (DERs) encompass a range of small, modular power-generating technologies situated near the point of electricity consumption, such as in homes or businesses, rather than at large, central power plants. All of the given four units can be labelled as DER. Option (d) is the correct answer.