PAX Prep NLN Verbal Comprehension

Passages Answered,

The way Things Work

It was the ancient Greeks who first had the idea that everything is made up of elements. They

conjured up just four of them-earth, fire, wind and water. As it turned out, the idea was right but

the elements were wrong. Modern elements are less evocative but more numerous. They make

up just over one hundred basic substances. Some are commonplace, like hydrogen, oxygen, iron

and carbon; others are rare and precious, such as mercury, uranium and gold.

Purely by the power of reason, the Greeks also made another fundamental discovery, which is

that all things consist of particles called atoms. Elements are substances that contain only one

kind of atom. All other substances are compounds of two or more elements in which the atoms

group together to form molecules.The way molecules behave governs the workings of many

machines, in particular machines such as ships, airplanes, pumps, refrigerators and combustion

engines, all of which harness the ancient elements and set molecules to work.

The idea that everything is made of particles takes some imagination to understand. For example,

as you read this, molecules of oxygen and nitrogen traveling at supersonic speed are bombarding

you from all directions. The reason that you are unaware of this is that the molecules (which

along with those others gases, make up the air) are on the small side. You could get about 400

million million of them into an empty matchbox. In fact, it would be truer to say that you could

get these millions of molecules out of the matchbox, because the molecules of gases are so

hyperactive that they will fill any space open to them. Like five-year-olds, they dash about in all

directions. With unflagging energy, crashing into any obstacle they meet. In liquids, the

molecules are less energetic and go haphazardly about ion small groups, rather like drunken

dancers prone to colliding with the walls of the dance hall. The molecules in solids are the least

energetic; they just huddle together like a flock of sheep shuffling around in a field.

However invisible molecules might be, their existence does explain the properties and behavior

of materials that are put to use in machines. In a solid, the molecular bonds are strong and hold

the molecules firmly together so that the solid is hard and rigid. The weaker bonds between

liquid molecules pull them together to give the liquid a set volume, but the bonds are sufficiently

weak to allow the liquid to flow. The bonds between gas molecules are weaker still. They enable

the molecules to move apart so the gas expands and fills any space. In all materials, the

molecules urge to stick together or spread apart is put to use in machines and devices as different

as the rocket, the toilet tank and the aqualung.

David Macaulay, The way Things Work Houghton Mifflin Co 1988

Question

1 of 5

In the context of this article, the word conjured as used in paragraph one means?

A.) swept

B.) intertwined

C.) imagined

D.) conferred. - answer: imagined

The way Things Work