PSAT Reading Practice Question 549

Question: 549

The following passages are adapted from 2013 articles about microwaves.
passage 1
It's a common fixture in household
kitchens all across the United States, but
remarkably few of us who use them have any
real idea of how our microwave ovens work.
05Contrary to most other food-heating appliances—
the toaster, the convection oven, and
the stove for instance—the microwave itself
has no internal heating element: flame, coil,
or otherwise. Instead, the microwave oven
10uses the principle of dipole rotation to generate
heat from the molecules within the food
itself.
Polar molecules, like a bar magnet, possess
an electrical dipole moment, and, when
15introduced to a strong enough electromagnetic
field, will align their positive and negative
ends appropriately. The microwave oven
produces a strong electromagnetic field,
but this is not enough to generate heat from
20within the food.
As anyone who has watched a bag of
instant popcorn expand knows, the tray
inside of a microwave oven rotates as the
food cooks. This rotation has the interesting
25effect of increasing the kinetic energy of the
food's polar molecules as they too must constantly
rotate in order to remain aligned with
the field. As they do so, these molecules rub
and grind against their neighbors, converting
30their kinetic energy into intermolecular friction,
thus evolving heat. In fact, the motion
of molecules is so directly related to internal
heat that one can actually calculate a material's
exact temperature by averaging the
35kinetic energy of the atoms and molecules
that comprise it.
passage 2
It is probable that humans have been
cooking since not long after our ancestors
harnessed the power of fire some several
40hundred thousand years ago. Since that
time, the sophistication of our technology
has increased more or less exponentially,
and the technology of cooking is no exception.
Insofar as it pertains to heat, the nature
45of culinary innovation has fallen primarily
into one of two categories common to many
technology arcs: speed and precision.
The first great breakthrough in cooking
had to be the division of fires into their
50component functions. That is, a campfire
used to produce light or to heat a large area
is not typically the ideal fire for cooking.
Once a fire ring was designated specifically
for the preparation of food, the earliest
55earthen stoves almost certainly began to
evolve shortly afterward and would have
significantly increased the degree to which
primitive cooks could distribute heat evenly.
Discovered in the Ukraine, the oldest known
60stoves appear to date from about 30,000
years ago and were used primarily to bake
mammoth meat.
The stove and the oven remain to this day
our most commonly used cooking technologies.
65Innovations in the field of heating
elements have frequently ameliorated the
mechanism without much change to the
principle design. The commercialization
of natural gas in late 17th-century England
70eventually gave cooks the ability to manipulate
their cooking flame precisely as well as
the convenience of instantaneous ignition.
To this day, gas ranges are preferred by many
professional chefs.
75The electric oven is an anomaly in the
cooking technology arc, as it developed
nearly one hundred years after the gas oven
but is markedly slower and often less precise.
Nonetheless, advancements in conductive
80materials, convection technology, and electromagnetic
induction have tremendously
improved on the efficacy of the original
resistive-coil ranges.
Electricity in the kitchen, of course, ushered
85in a new age of powered cooking appliances.
Perhaps none is more curious, clever,
and common than the microwave oven. The
epitome of speed cooking, the microwave
uses a wholly different approach to heating
90food than any of its predecessors—however,
its remarkable swiftness comes at the expense
of precision, particularly when dealing with
physically dense foodstuffs. In consequence,
the microwave is a fantastic device for thawing
95stored vegetables but should hardly be relied
upon to properly prepare, say, a Thanksgiving
turkey or perhaps a mammoth steak.
Polar Substances
Nonpolar Substances
Ethanol
Water
Glucose
Ethyl alcohol
Acetic acid
Methane
Carbon dioxide
Ethylene
Gasoline
Hexane

As it is used in line 31, "evolving" most nearly means

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