General Science on the ASVAB, four sciences in one

In most substances, which state of matter has its particles packed most closely together?

1. Gas
   Gas particles are far apart and move freely, which is why a gas can be squeezed into a smaller volume.
2. Solid
   In a solid, particles are locked in place and touching, so they are packed most closely; water, whose ice floats, is a rare exception.
3. Liquid
   Liquid particles are close but slide past one another; in most substances they sit slightly farther apart than in the solid.
4. Plasma
   Plasma is a very hot gas of charged particles, even more spread out than an ordinary gas.

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Which of the following is a characteristic of acids?

1. They turn red litmus paper blue
   Bases turn red litmus blue; acids do the reverse and turn blue litmus red.
2. They have a pH of 7
   A pH of 7 is neutral, like pure water; an acid's pH falls below 7.
3. They give a solution a pH below 7
   Acids release hydrogen ions in water, which puts their pH below 7, the neutral point.
4. They produce hydroxide ions in water
   Releasing hydroxide ions is the mark of a base, the opposite of an acid.

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In the DNA double helix, which bases pair with each other?

1. Adenine with thymine and cytosine with guanine
   Adenine bonds to thymine and cytosine to guanine; each pair joins one large base to one small base, so the helix keeps an even width.
2. Adenine with cytosine and guanine with thymine
   Adenine–cytosine and guanine–thymine cannot form matching hydrogen bonds; DNA pairs A only with T and C only with G.
3. Adenine with guanine and cytosine with thymine
   Adenine and guanine are both large bases; pairing two large bases would make the helix bulge, and these pairs do not bond.
4. Adenine with uracil and cytosine with guanine
   Uracil replaces thymine in RNA, not DNA; A–U pairing happens when RNA is made or read.

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At which type of plate boundary is new oceanic crust formed?

1. Divergent boundary
   A divergent boundary is where plates pull apart, as along the Mid-Atlantic Ridge, magma rises into the gap and cools into new oceanic crust.
2. Subduction boundary
   A subduction zone is a convergent boundary where oceanic crust sinks back into the mantle, the opposite of where it forms.
3. Transform boundary
   At transform boundaries such as the San Andreas Fault, plates slide past each other and crust is neither made nor destroyed.
4. Convergent boundary
   At convergent boundaries plates collide, building mountains or destroying crust rather than making it.

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Which best describes Earth's lithosphere?

1. The whole mantle, down to the outer core
   Most of the mantle lies below the lithosphere; only its rigid top is part of it.
2. The liquid iron-nickel layer around the inner core
   A liquid iron-nickel layer is the outer core, thousands of kilometers below the surface.
3. The soft, partly melted layer the plates ride on
   The soft layer the plates move over is the asthenosphere, just below the lithosphere.
4. The crust plus the rigid uppermost part of the mantle
   The lithosphere is Earth's stiff outer shell: the crust together with the rigid uppermost mantle, broken into tectonic plates.

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Which process forms sedimentary rock?

1. Heat and pressure change an existing rock
   Changing an existing rock by heat and pressure, without melting it, is how metamorphic rock forms.
2. Lava cools quickly at the surface
   Fast cooling of lava at the surface makes extrusive igneous rock such as basalt.
3. Magma cools and hardens slowly deep underground
   Slow cooling of magma underground makes intrusive igneous rock such as granite.
4. Loose grains are compacted and cemented together
   Sedimentary rock forms when sand, mud or shells are buried, pressed together and glued by minerals that crystallize between the grains.

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An oxygen atom (atomic number 8) gains two electrons to achieve a stable electron configuration. What is the charge on the resulting ion, and which noble gas electron configuration does it attain?

1. 1−, neon
   A 1− charge would mean only one electron gained, for 9 electrons, which matches no noble gas.
2. 2+, neon
   Gaining electrons adds negative charge; 2+ would come from losing two electrons, the sign error.
3. 2−, neon
   Oxygen has 8 electrons; gaining 2 gives 10, the arrangement of neon, and two extra electrons make the charge 2−.
4. 2−, argon
   Argon has 18 electrons; an oxygen ion with 10 electrons matches neon, not argon.

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Stars rise in the east and set in the west every day, but the constellations visible at midnight change over several months. Which motions of Earth account for these observations?

1. Revolution for both daily and seasonal patterns
   Revolution, one orbit, takes a year, far too slow to make stars rise and set every day.
2. Rotation for daily rising and setting; revolution for seasonal constellations
   Earth's daily spin makes stars rise and set; its yearly orbit slowly turns the night side toward different constellations.
3. Rotation for both daily and seasonal patterns
   Rotation repeats the same sky each day, so on its own it cannot change which constellations are up at midnight over the months.
4. Revolution for daily rising and setting; rotation for seasonal constellations
   This swaps the two motions: the daily effect comes from the spin and the slow seasonal change from the orbit.

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In an animal cell, most of the ATP the cell uses for energy is produced in the

1. chloroplasts
   Chloroplasts capture light for photosynthesis in plants and algae; animal cells have none.
2. mitochondria
   Mitochondria run the oxygen-using stages of cellular respiration, which release most of a cell's ATP from glucose.
3. ribosomes
   Ribosomes build proteins from amino acids; they use ATP but do not make it.
4. nucleus
   The nucleus holds the DNA and directs the cell, but it is not where food is broken down for energy.

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In pea plants, the allele for tall stems (T) is dominant over the allele for short stems (t). If two Tt plants are crossed, what fraction of the offspring is expected to be short?

1. 1/4
   A Tt × Tt cross gives TT, Tt, Tt and tt in equal shares; only tt plants are short, so 1/4 of the offspring.
2. 1/3
   1/3 comes from listing the three genotypes TT, Tt and tt as if they were equally likely; Tt turns up twice as often as each of the others.
3. 1/2
   1/2 is the share of Tt offspring here, or the short share from a Tt × tt cross; with two Tt parents short plants are rarer.
4. 3/4
   3/4 is the share of tall plants (TT plus Tt), the dominant trait, not the short one.

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In the food chain grass → grasshopper → frog → snake → hawk, the frog is a

1. tertiary consumer
   Tertiary comes from counting the grass as the first link of consumers; in this chain the snake is the tertiary consumer.
2. producer
   A producer makes its own food by photosynthesis; in this chain that is only the grass.
3. secondary consumer
   Grass is the producer, the grasshopper that eats it is the primary consumer, and the frog that eats the grasshopper is the secondary consumer.
4. primary consumer
   A primary consumer eats producers directly; the frog eats an animal, which puts it one level higher.

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Sound travels fastest through which of these?

1. Water
   Sound moves at about 1,500 m/s in water, faster than in air but far slower than in steel.
2. Steel
   Sound is a vibration passed from particle to particle; in steel it moves at about 5,900 m/s, roughly 17 times faster than in air.
3. A vacuum
   A vacuum has no particles to vibrate, so sound cannot travel through it at all.
4. Air
   Air is the slowest medium of these, about 343 m/s at room temperature, because gas particles are far apart.

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Energy from the Sun reaches Earth across the nearly empty space between them by

1. radiation
   Radiation, as visible light and infrared, needs no matter to travel, so it carries the Sun's energy through space.
2. convection
   Convection needs a moving fluid such as air or water; it spreads heat through the atmosphere but cannot cross space.
3. conduction
   Conduction passes heat between particles that touch, and space has almost no particles to pass it along.
4. reflection
   Reflection only bounces light off a surface; it changes the light's direction but is not how energy crosses from the Sun.

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An astronaut has a mass of 80 kg on Earth. On the Moon, where gravity is about one-sixth as strong, the astronaut's mass is

1. 0 kg
   Zero mass would mean the body had vanished; feeling light or weightless is not losing matter.
2. 13 kg
   80 ÷ 6 ≈ 13 is the right way to scale weight, not mass; this answer mixes up the two.
3. 80 kg
   Mass is the amount of matter in the body and does not depend on gravity, so it stays 80 kg; only the weight drops to about one-sixth.
4. 480 kg
   80 × 6 = 480 scales the wrong way, and mass does not change with gravity at all.

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Atoms of carbon-12 and carbon-14 differ in their number of

1. protons
   The number of protons defines the element; any atom with 6 protons is carbon, so this cannot differ.
2. electron shells
   Electron shells are filled by the same 6 electrons in both, which is why the two isotopes react alike.
3. electrons
   Neutral atoms of both have 6 electrons; changing the electron count makes an ion, not a different isotope.
4. neutrons
   Both are carbon, so both have 6 protons; the mass numbers 12 and 14 mean 6 and 8 neutrons.

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