Question

What is called as ‘black gold’?

• A. Hydrocarbon
• B. Coal gas
• C. Petroleum
• D. Ether

Answer 1

The correct option is C

Petroleum

Explanation for correct option

(C) Petroleum

Black gold:

• It is a term that is applied to petroleum or oil.
• It contains hydrocarbons with various molecular weights that are present naturally.

Reasons for petroleum is called ‘black gold’

• Extraction is highly expensive.
• It has a significant economic value.
• The produced crude oil is initially black in color before turning yellowish, therefore the name gold.

Explanation for incorrect option

(A)Hydrocarbon

• “The name 'hydrocarbon' is self-explanatory, referring to the compounds of carbon and hydrogen only.”
• Hydrocarbons are commonly used as fuels. Examples of hydrocarbons are LPG and CNG.

(B)Coal gas

• Coal gas is a combustible gaseous fuel that is produced from coal and delivered to the customer through a distribution network of pipes.
• When coal is heated vigorously without the presence of air, coal gas is formed.

(D)Ether

• The substitution of a hydrogen atom in a hydrocarbon by an alkoxy or aryloxy group$(\mathrm{R}–\mathrm{O}/\mathrm{Ar}–\mathrm{O})$ yields ‘ethers’.
• Hence, all the other options (A), (B) and (D) are incorrect.

Therefore, the correct option is (C). Petroleum is called as ‘black gold’.