Organic Chemistry F. The Fuel

41. Compressed Natural Gas (CNG) is mainly composed of - [R.A.S./R.T.S. (Pre) 2021, U.P.P.C.S. (Pre) 2022]

(a) Propane
(b) Butane
(c) Methane
(d) Ethane

Correct Answer: (c) Methane

Solution:CNG is made by compressed natural gas which is mainly composed of methane (CH₄). It is a mixture of hydrocarbons, which is found deep inside Earth and has approx. 80% to 90% of methane.

42. Consider the following statements: [I.A.S. (Pre) 2005]

Liquefied Natural Gas (LNG) is liquefied under extremely cold temperatures and high pressure to facilitate storage or transportation in specially designed vessels.
The first LNG terminal in India was built in Hassan.
Natural Gas Matters (NGM) are separated from LPG, and these include ethane, propane, butane, and natural gasoline.

Which of the statements given above is/are correct?

(a) 1 only
(b) 1 and 3
(c) 2 and 3
(d) 1, 2 and 3

Correct Answer: (a) 1 only

Solution:CNG is made by compressed natural gas which is mainly composed of methane (CH₄). It is a mixture of hydrocarbons, which is found deep inside Earth and has approx. 80% to 90% of methane.

43. Oxygen is absent in - [66th B.P.S.C. (Pre) (Re. Exam) 2020, 65th B.P.S.C. (Pre) 2019]

Correct Answer: (a) Kerosene

Solution:Kerosene is a combustible hydrocarbon liquid derived from petroleum. It is a mixture of hydrocarbons and does not contain oxygen. Oxygen is present in glass, soil, and cement.

44. Gasohol is - [Uttarakhand P.C.S. (Pre) 2005]

(a) Ethyl alcohol + Petrol
(b) Natural gas + Ethyl alcohol
(c) Any gas dissolved in alcohol
(d) Ethyl alcohol + Kerosene oil

Correct Answer: (a) Ethyl alcohol + Petrol

Solution:Gasohol, a gasoline extender made from a mixture of gasoline (petrol) and ethanol (often obtained by fermenting agricultural crops). Gasohol has higher octane or anti-knock properties by which it burns more slowly, coolly, and completely.

45. Gasohol is a mixture of - [U.P.P.C.S. (Mains) 2016]

(a) Gasoline and Methanol
(b) Gasoline and Ethanol
(c) Gasoline and Propanol
(d) Methanol and Ethanol

Correct Answer: (b) Gasoline and Ethanol

Solution:Gasohol, a gasoline extender made from a mixture of gasoline (petrol) and ethanol (often obtained by fermenting agricultural crops). Gasohol has higher octane or anti-knock properties by which it burns more slowly, coolly, and completely.

46. Consider the following statements: [U.P.P.C.S. (Mains) 2009]

Coal, petroleum, and natural gas are fossil fuels.
Gasohol is a mixture of benzene and alcohol.
Geothermal energy is a non-conventional energy source.
Gobar gas contains mainly methane.

(a) Only 1 and 2 are correct
(b) Only 2 and 3 are correct
(c) Only 1, 2 and 3 are correct
(d) 1, 3 and 4 are correct

Correct Answer: (d) 1, 3 and 4 are correct

Solution:Fossil fuels are hydrocarbons primarily coal, fuel oil, or natural gas formed from the remains of dead plants and animals. Sometimes, they are known as mineral fuels. Fossil fuels are fuels formed by a natural process such as anaerobic decomposition of buried dead organisms. Ethanol fuel mixtures have "E" numbers, which describe the percentage of ethanol fuel in the mixture by volume. E85 is 85% denatured ethanol fuel and 15% gasoline. Low-ethanol blends from E5 to E25 are also known as gasohol.

47. To avoid 'knocking' of the engine of a car, which one of the following is used as an anti-knocking agent? [U.P.P.C.S. (Pre) 1998]

(a) Ethyl alcohol
(b) Butane
(c) Tetraethyl Lead
(d) White Petrol

Correct Answer: (c) Tetraethyl Lead

Solution:Tetraethyl Lead (CH₃CH₂)₄Pb is the chief anti-knock agent for automotive gasoline or petrol. In the hot cylinder of a gasoline engine, the bonds between the lead atom and the ethyl groups are broken. Upon combustion, the lead atom forms lead oxide (PbO), which prevents fractions of the fuel mixture from burning too quickly and causing a highly undesirable engine knock. Thus, it is mixed with petrol to increase its anti-knocking rate.

48. Tetraethyl Lead (TEL) is added to petrol : [U.P.P.C.S. (Pre) 1996]

(a) To prevent it from freezing
(b) To increase its flash point
(c) To increase its anti-knocking rating
(d) To increase its boiling point

Correct Answer: (c) To increase its anti-knocking rating

Solution:Tetraethyl Lead (CH₃CH₂)₄Pb is the chief anti-knock agent for automotive gasoline or petrol. In the hot cylinder of a gasoline engine, the bonds between the lead atom and the ethyl groups are broken. Upon combustion, the lead atom forms lead oxide (PbO), which prevents fractions of the fuel mixture from burning too quickly and causing a highly undesirable engine knock. Thus, it is mixed with petrol to increase its anti-knocking rate.

49. Which one of the following is used as an anti-freeze for the automobile engines? [I.A.S. (Pre) 1997]

(a) Propyl alcohol
(b) Ethanol
(d) Ethylene glycol
(d) Ethylene glycol

Correct Answer: (d) Ethylene glycol

Solution:An antifreeze is an additive that lowers the freezing point of a water-based liquid. An antifreeze mixture is used to achieve freezing point depression for cold environments and also achieves boiling point elevation to allow higher coolant temperature.

50. Diesel used in heavy vehicles for - [U.P.P.C.S. (Pre) 1992]

(a) Extra mileage and save engine
(b) Low expense and save the fuel
(c) High power and economic saving
(d) Being cheaper than low petrol

Correct Answer: (c) High power and economic saving

Solution:An internal combustion engine transforms the chemical energy in fuel to mechanical rotational energy. Diesel engines, which have been in existence for over a century, are the most versatile and economical engine used in heavy vehicles. Today's direct-injection diesel engines are more rugged, powerful, durable, and reliable than gasoline engines, using fuel much more efficiently as well.