THE EXPLANATION THAT OUR (A) INSTRUCTOR GAVE US (B) WAS DIFFERENT T...

60.The explanation that our (A) instructor gave us (B) was different to (C) the

one your (D) gave you.

Read the following passage and mark the letter A, B, C, or D to indicate the correct

answer to each of the following questions.

Petroleum products, such as gasoline, kerosene, home heating oil, residual fuel oil, and

lubricating oils, come from one source of crude oil found below the earth’s surface, as

well as under large bodies of water, from a few hundred feet below the surface to as deep

as 25,000 feet into the earth’s interior. Sometimes crude oil is secured by drilling a hole

through the earth, but more dry holes are drilled than those producing oil. Pressure at the

source of pumping forces crude oil to the surface. Crude oil wells flow at varying rates,

from ten to thousands of barrels per hour. Petroleum products are always measured in 42-

gallon barrels.

Petroleum products vary greatly in physical appearance: thin, thick, transparent or opaque,

but regardless, their chemical composition is made up of only two elements: carbon and

hydrogen, which form compounds called hydrocarbons. Other chemical elements found

in union with the hydrocarbons are few and are classified as impurities. Trace elements

are also found, but these are of such minute quantities that they are disregarded. The

combination of carbon and hydrogen forms many thousands of compounds which are

possible because of the various positions and joining of these two atoms in the

hydrocarbon molecule.

The various petroleum products are refined from the crude oil by heating and condensing

the vapors. These products are the so-called light oils, such as gasoline, kerosene, and

distillate oil. The residue remaining after the light oils are distilled is known as heavy or

residual fuel oil and is used mostly for burning under boilers. Additional complicated

refining processes rearrange the chemical structure of the hydrocarbons to produce other

products.