QUESTION: 53

What is the underlying principle behind the operation of a jet engine?
Exhibit:

Exhibit:

The engine burns air from the exhaust to decelerate the plane.
Shooting a jet of gases backward thrusts the plane forward.
An electric heater is used to form hot gases.
Minimizing the friction in the engine increases velocity.
The engine allows the plane a cruising velocity faster than the speed of sound.

Answer(s): B

Density is the relationship of the mass of an object to its volume. A formula that describes density isdensity = mass/volumewhere mass is the quantity of matter present and volume measures how much space the matter occupies.
Suppose that a tanker truck overturns, causing hazardous vapors to leak from the tank. As the vapors leak out, they appear to fall to the ground and then travel along the ground.
Which conclusion about density may be correctly drawn from this information?

The weight of the hazardous vapor is greater than that of the truck.
A safe place to go would be the nearest basement.
The density of the hazardous vapor is greater than that of water.
Spraying the tank truck with water would be the safest thing to do.
The density of the hazardous vapor is greater than that of air.

Answer(s): E

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QUESTION: 55

Cholera is a disease caused by a bacterium that is transmitted by water, shellfish, and raw vegetables. The major symptom is severe diarrhea. Epidemics of cholera in the Americas, common in the 19th century, are much less frequent now with the advent of modern medicine and improved methods of hygiene.
However, in 1991, the number of cholera epidemics increased again in one South American country, causing over 4000 deaths.
The high number of cases of cholera in the South American country noted above was most probably due to which factor?

prolonged smoking of cigarettes
lack of variety in foods
poor water and sewage treatment
eating the wrong kinds of foods
widespread overuse of antibiotics

Answer(s): C

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QUESTION: 56

Rosa fills five small aquariums with equal amounts of pond water. She places various combinations of fish, plants, and/or snails in each aquarium except A, which contains only pond water. Rosa seals all the aquariums and stores them at room temperature under an aquarium light. The light provides the energy for photosynthesis in green plants and production of food and oxygen.

In which aquarium would the animals live for the longest period?

Answer(s): C

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