PASSAGE 1The oxidation of exhaust gases is one of the primary sources of the world’s
pollution. The brown haze that is poised over some of the world’s largest cities is
properly called photochemical smog; it results from chemical reactions that take place
in the air, using the energy of sunlight. The production of smog begins with gases are
created in the cylinders of vehicle engines. It is there that oxygen and nitrogen gas
combine as the fuel burns to form nitric oxide (NO), a colorless gas. The nitric oxide is
forced out into the air through the vehicle tailpipe along with other gases. When the gas reaches the air, it comes into contact with available oxygen from
the atmosphere and combines with the oxygen to produce nitrogen dioxide (NO2),
which is a gas with a brownish hue. This nitrogen dioxide plays a role in the formation
of acid rain in wetter or more humid climates and tends to decompose back into nitric
oxide as it releases an oxygen atom from each molecule; the released oxygen atoms
quickly combine with oxygen (O2) molecules to form ozone (O3). The brownish
colored nitrogen dioxide is partially responsible for the brown color in smoggy air; the
ozone is the toxic substance that causes irritation to eyes.
1. The word poised in paragraph 1 is closest in meaning to
(A) interacting
(B) sitting
(C) blowing
(D) poisoning
2. The phrase take place in paragraph 1 is closest in meaning to
(A) position themselves
(B) put
(C) are seated
(D) occur
3. The word forced in paragraph 1 could best be replaced by
(A) obliged
(B) required
(C) pushed
(D) commanded
4. The word hue in paragraph 2 is closest in meaning to
(A) color
(B) odor
(C) thickness
(D) smoke
5. The phrase plays a role in paragraph 2 is closest in meaning to
(A) makes fun of
(B) serves a function in
(C) acts the part of
(D) moves about