1. Which one of the following is the correct sequential order in which these appeared under simulated primitive earth conditions?
(a) Methane, Hydrogen Cyanide, Nitrile, Amino Acid
(b) Hydrogen Cyanide, Methane, Nitrile, Amino Acid
(c) Amino Acid, Nitrile, Hydrogen Cyanide, Methane
(d) Nitrile, Amino Acid, Methane, Hydrogen Cyanide
[I.A.S. (Pre) 1994]
Ans. (a) Methane, Hydrogen Cyanide, Nitrile, Amino Acid
- Under conditions that imitate the Earth’s primitive environment, Methane, Hydrogen Cyanide, Nitrile, and Amino Acid come in that order.
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2. Which is the fundamental element of all organic compounds?
(a) Nitrogen
(b) Oxygen
(c) Carbon
(d) Brimstone
[56th to 59th B.P.S.C. (Pre) 2015, U.P.U.D.A./L.D.A. (Pre) 2001]
Ans. (c) Carbon
- Carbon is the main component of all organic compounds (including compounds from living things).
- Organic compounds are a big group of chemicals where one or more carbon atoms are connected to atoms of other elements, usually hydrogen, oxygen, or nitrogen.
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3. In all bio-compounds the most necessary fundamental element is –
(a) Sulphur
(b) Carbon
(c) Oxygen
(d) Nitrogen
[U.P.P.C.S. (Mains) 2015]
Ans. (b) Carbon
- Carbon is the basic component of all organic substances (which includes substances from living things).
- Organic compounds are a large group of chemicals that are connected by carbon and other elements such as hydrogen, oxygen, or nitrogen.
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4. Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?
(a) Hydrogen, Oxygen, Sodium
(b) Carbon, Hydrogen, Nitrogen
(c) Oxygen, Calcium, Phosphorus
(d) Carbon, Hydrogen, Potassium
[I.A.S. (Pre) 2012]
Ans. (b) Carbon, Hydrogen, Nitrogen
- Biologists think six elements were the main cause of life on Earth.
- They are Hydrogen, Oxygen, Carbon, Nitrogen, Phosphorus and Sulphur.
- All living things on Earth are made up of these compounds such as proteins, nucleic acids, carbohydrates, vitamins and hormones.
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5. Which one of the following is the correct sequence in increasing order of molecular weights of the hydrocarbons?
(a) Methane, Ethane, Propane and Butane
(b) Propane, Butane, Ethane and Methane
(c) Butane, Ethane, Propane and Methane
(d) Butane, Propane, Ethane and Methane
[I.A.S. (Pre) 2001]
Ans. (a) Methane, Ethane, Propane and Butane
- The hydrocarbons go in order of increasing atomic weight, from methane (CH4) to ethane (C2H6), propane (C3H8), and butane (C4H10
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6. A hydrocarbon in which two carbon atoms are joined by a double bond is called an :
(a) Alkane
(b) Alkene
(c) Alkyne
(d) Ionic bond
(e) None of the above/More than one of the above
[63rd B.P.S.C. (Pre) 2017]
Ans. (b) Alkene
- A hydrocarbon with two carbon atoms connected by a double bond is called an alkene.
- Alkenes typically have the formula Cn H2n.
- They are also known as olefins.
- The first three members of this group are Ethylene (C2 H4), Propylene (C3 H6) and Butylene (C4 H8).
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7. Which of the following gases is used in cigarette lighters?
(a) Butane
(b) Methane
(c) Propane
(d) Radon
[56th to 59th B.P.S.C. (Pre) 2015]
Ans. (a) Butane
- Butane is a type of gas that is flammable and made up of four hydrogen atoms and 10 carbon atoms.
- It is often used in cigarette lighters and is also called Natural Gas Liquid.
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8. Leakage of which of the following gases had caused the Bhopal Gas Tragedy?
(a) Methyl isocyanate
(b) Carbon monoxide
(c) Nitric oxide
(d) Sulphur dioxide
[Uttarakhand P.C.S. (Pre) 2012]
Ans. (a) Methyl isocyanate
- The Bhopal Gas Tragedy was an accident that happened at a pesticide plant in Bhopal, India.
- On the night of 2-3 December 1984, the plant released 42 tonnes of poisonous methyl isocyanate gas, affecting over 500,000 people.
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9. The Bhopal Gas Tragedy was caused due to the leakage of :
(a) Methyl isocyanate
(b) Nitrogen dioxide
(c) Sulphur dioxide
(d) Carbon monoxide
[U.P.P.C.S. (Pre) 2017]
Ans. (a) Methyl isocyanate
- The Bhopal Gas Tragedy was an accident that happened at a pesticide plant in Bhopal, India.
- On the night of December 2nd and 3rd, 1984, the plant released 42 tonnes of a toxic gas called methyl isocyanate, which affected more than 500,000 people.
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10. When did the Bhopal Gas tragedy happen?
(a) 2-3 Dec. 1984
(b) 2-3 Nov. 1984
(c) 2-3 Dec. 1985
(d) 2-3 Nov. 1985
[M.P.P.C.S. (Pre) 2013]
Ans. (a) 2-3 Dec. 1984
- On the night of December 2nd-3rd, 1984, a plant released 42 tons of poisonous gas called methyl isocyanate (MIC), affecting more than half a million people.
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11. From the decomposition of which of the following printing ink is formed :
(a) Acetylene
(b) Methane
(c) Carbon tetrachloride
(d) Benzene
[Jharkhand P.C.S. (Pre) 2003]
Ans. (b) Methane
- Methane is an invisible, tasteless, and smell-less gas found in wetlands, which is created when organic matter breaks down and is emitted by coal.
- It’s used to make carbon black, a material used for producing black printing ink.
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12. Methane gas producing field is –
(a) Wheat field
(b) Paddy field
(c) Cotton field
(d) Groundnut f eld
[U.P.P.C.S. (Pre) 2014]
Ans. (b) Paddy field
- Rice paddies are a big cause of methane in the atmosphere, and it is estimated that they produce between 50 and 100 million tons of the gas each year.
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13. Which of the following is correctly matched?
| List-I |
List – II |
| 1. Biogas |
Insecticide |
| 2. Electrocardiography |
Heart disorder |
| 3. D.D.T |
Cow-dung |
| 4. Nicotine |
Tobacco |
Code :
(a) 1, 2 and 4
(b) 2, 3 and 4
(c) 2 and 3
(d) 2 and 4
[U.P. Lower Sub. (Pre) 2002]
Ans. (d) 2 and 4
- In rural areas, biogas plants provide gas for cooking and lighting.
- ECGs are used to identify heart diseases. D.D.T. is a type of pesticide and nicotine is found in tobacco which has a very negative effect on health.
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14. Which one of the following chemicals helps in fruit ripening?
(a) Ethephon
(b) Atrazine
(c) Isoproturan
(d) Malathion
[U.P. U.D.A./L.D.A. (Pre) 2010, U.P.P.C.S. (Pre) 2005]
Ans. (a) Ethephon
- Ethephon (or ethrel) is a popular chemical used in fruit ripening.
- It is a type of formula that produces ethylene when mixed with water at a specific pH. It can be used as an alternative to calcium carbide.
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15. Which of the following chemicals is used for ripening?
(a) Sodium Chloride
(b) Calcium Carbide
(c) Potassium Chloride
(d) None of the above
[U.P.P.C.S. (Mains) 2011]
Ans. (b) Calcium Carbide
- For artificially ripening fruit, calcium carbide (with the chemical formula CaC2) is sometimes used to produce a ripening gas similar to Ethylene.
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16. Calcium carbide is used for artificial ripening of green fruits because it produces :
(a) Methylene
(b) Auxin
(c) Acetylene
(d) Florigen
[R.A.S./R.T.S. (Pre) 2016]
Ans. (c) Acetylene
- In some cases, calcium carbide (with the chemical formula CaC2) is used to speed up the ripening of fruit. It produces acetylene gas, which is similar to ethylene and helps fruit ripen quicker.
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17. Fruit ripening is promoted by which of the following?
(a) Carbon dioxide
(b) Sulphur dioxide
(c) Nitrogen
(d) Ethylene
[U.P.R.O./A.R.O (Pre) 2014]
Ans. (d) Ethylene
- Ethylene gas is a special kind of hormone found in nature that helps speed up the ripening of fruits.
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18. Which of the following gas mixtures is used in welding gas?
(a) Acetylene and Hydrogen
(b) Oxygen and Acetylene
(c) Hydrogen and Oxygen
(d) Hydrogen and Helium
[Uttarakhand P.C.S. (Pre) 2005]
Ans. (b) Oxygen and Acetylene
- Gas welding uses a combination of oxygen and acetylene.
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19. Gases used in welding are :
(a) Oxygen and hydrogen
(b) Oxygen and nitrogen
(c) Oxygen and acetylene
(d) Hydrogen and acetylene
(e) None of the above/More than one of the above
[63rd B.P.S.C. (Pre) 2017]
Ans. (c) Oxygen and acetylene
- Gas welding involves using a combination of oxygen and acetylene.
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20. Consider the following statements about acetylene :
1. It is used in the welding industry.
2. It is a raw material for preparing plastics.
3. It is easily obtained by mixing silicon carbide and water.
Of these statements
(a) 1 and 2 are correct
(b) 1 and 3 are correct
(c) 2 and 3 are correct
(d) 1, 2 and 3 correct
[I.A.S. (Pre) 1998]
Ans. (a) 1 and 2 are correct
- Acetylene, also known as Ethyne (C2 H2), is used for welding.
- Chloroethane is produced from acetylene and is used in the plastic industry.
- Acetylene is made by combining calcium carbide (not silicon carbide) with water.
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21. For benzene which of the following statements is true?
(a) It has six sigma and six pi bonds
(b) It has twelve sigma and six pi bonds
(c) It has twelve sigma and three pi bonds
(d) It has six sigma and three pi bonds
(e) None of the above.
[Chhattisgarh P.C.S. (Pre) 2014]
Ans. (c) It has twelve sigma and three pi bonds
- Benzene is a very important chemical compound made up of 6 Carbon and 6 Hydrogen atoms.
- Its structure is like a hexagon shape with double bonds going back and forth.
- There are 6 sigma bonds between the Carbon atoms and 6 sigma bonds between Carbon and Hydrogen. Additionally, there are 3 pi bonds between the Carbon atoms.
- This makes a total of 12 sigma and 3 pi bonds in the Benzene molecule.
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22. Numbers of sigma and pi bonds in benzene are:
(a) 3, 3
(b) 3, 6
(c) 12, 3
(d) 12, 6
(e) None of the above / More than one of the above
[66th B.P.S.C. (Pre) 2020]
Ans. (c) 12, 3
- Benzene is a significant organic chemical made of 6 Carbon and 6 Hydrogen atoms.
- Its chemical structure looks like a hexagon with double bonds in between the sides.
- It has 6 sigma bonds between Carbon atoms and 6 sigma bonds between Carbon atoms and Hydrogen atoms. In addition, it has 3 pi bonds between Carbon atoms.
- This makes 12 sigma and 3 pi bonds in the Benzene molecule.
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