ASVAB — All Questions

A tendon in the human body attaches

• a.a bone to cartilage
• b.a muscle to a bone✓
• c.a muscle to a muscle
• d.a bone to a bone

A tendon is the tough cord that carries a muscle's pull through to the skeleton, which is how a contraction swings a bone at a joint. Ligaments are the tempting reverse: they tie bone to bone and limit travel, so a torn ligament loosens a joint while a torn tendon costs movement.

When a person inhales, the diaphragm

• a.contracts and moves downward✓
• b.relaxes and moves upward
• c.contracts and moves upward
• d.relaxes and moves downward

The diaphragm is a domed sheet of muscle, and contracting flattens it downward so the chest cavity enlarges, pressure inside drops below outside air pressure, and air flows in. Exhaling is the passive reverse, the muscle relaxing and doming upward. Air moves on pressure, not on pulling.

Metamorphic rock such as marble or slate is formed by

• a.slow cooling of molten magma
• b.evaporation of trapped sea water
• c.heat and pressure on buried rock✓
• d.compaction of layered sediment

Metamorphism recrystallizes a rock that stays solid, so heat and pressure turn limestone into marble and shale into slate without either one melting. Melting and cooling would make it igneous instead, and compacted sediment is how the original limestone formed, which is why that answer tempts.

New ocean floor is created at a mid-ocean ridge where two tectonic plates

• a.grind past each other sideways
• b.press together and fold upward
• c.move apart and magma rises✓
• d.collide and one plate sinks under

Where plates separate, pressure on the mantle beneath them drops, magma rises into the gap and freezes as fresh crust, which is why the seafloor is youngest at the ridge and older toward the continents. One plate sinking beneath another is the tempting reverse: subduction destroys crust.

Clouds form when

• a.sinking air warms and water vapor condenses
• b.rising air warms and water droplets evaporate
• c.rising air cools and water vapor condenses✓
• d.sinking air cools and water droplets freeze

Air expands and cools as it rises, and cooler air holds less water vapor, so once it reaches the dew point the vapor condenses onto dust to make droplets. Sinking air does the opposite, warming and drying out, which is why high pressure brings clear skies instead of cloud.

The ozone layer, which absorbs most of the sun's ultraviolet radiation, lies in which layer of the atmosphere?

• a.the stratosphere✓
• b.the ionosphere
• c.the troposphere
• d.the thermosphere

Ozone sits roughly 15 to 35 km up, and the heat released as it absorbs ultraviolet light is why the stratosphere grows warmer with height instead of colder. The troposphere tempts because it is the layer we live in and where weather happens, but it lies below the ozone shield.

Earth has seasons mainly because

• a.its orbit speeds up and slows down
• b.its distance from the sun varies
• c.the sun's output rises and falls
• d.its axis is tilted as it orbits✓

Earth's axis is tilted about 23.5 degrees and keeps pointing the same direction all year, so each hemisphere leans toward the sun for half the orbit and gets steeper rays and longer days. Distance is the classic misconception: Earth is nearest the sun in early January, northern midwinter.

Ocean tides on Earth are caused mainly by

• a.prevailing winds over the ocean
• b.the moon's gravitational pull✓
• c.the earth's magnetic field
• d.the spin of the moon on its axis

The moon's gravity pulls the ocean toward it and leaves a matching bulge on the opposite side of the planet, so a rotating Earth carries most coasts through two high tides a day. The sun raises tides too, but under half as strongly, because tidal pull falls off with distance cubed.

Dry ice changes directly from a solid to a gas without ever becoming liquid. This change is called

• a.evaporation
• b.condensation
• c.deposition
• d.sublimation✓

Sublimation is solid straight to gas with no liquid stage, which happens when the pressure is too low for the liquid form to be stable at that temperature. Deposition is the tempting reverse, gas straight to solid, which is how frost grows on a cold window without dew forming first.

An element's atomic number tells you the number of

• a.electron shells in its atoms
• b.protons inside its nucleus✓
• c.neutrons in its nucleus
• d.particles in its nucleus

The proton count defines the element, so changing it makes the atom a different element altogether. Neutron count varies between isotopes of one element, and protons plus neutrons give the mass number, which is why counting every nuclear particle is the tempting near miss here.

Elements in the same column, or group, of the periodic table react in similar ways because they have the same number of

• a.electrons in the outermost shell✓
• b.neutrons inside the nucleus
• c.protons inside the nucleus
• d.electron shells around the atom

Chemical behaviour is set by the outermost electrons, so every element in a column gains, loses or shares the same number of them and the whole group reacts alike. The number of shells is what changes going down a column, and it is what a row across the table has in common instead.

A solution with a pH of 4 is how much more acidic than a solution with a pH of 6?

• a.10 times as acidic
• b.100 times as acidic✓
• c.1,000 times as acidic
• d.2 times as acidic

The pH scale is base ten, so each whole unit is a tenfold change in hydrogen ion concentration. From 6 down to 4 is two steps, and 10 x 10 gives 100 times more acidic. Answering 2 comes from subtracting 6 - 4 and treating the scale as if it added rather than multiplied.

A log burns away and leaves a small pile of ash that weighs far less than the log did. The missing mass

• a.turned entirely into heat and light
• b.was destroyed in the reaction
• c.stayed in the ash as carbon
• d.escaped as gases and water vapor✓

Mass is conserved: burning rearranges atoms rather than destroying them, so the wood's carbon and hydrogen leave as carbon dioxide and water vapor while minerals remain as ash. Weigh a sealed fire and nothing is lost. Heat and light come from bond changes, not from matter vanishing.

Which of the following is a compound rather than a mixture?

• a.ocean seawater
• b.carbon dioxide✓
• c.ordinary air
• d.stainless steel

A compound has its elements chemically bonded in a fixed ratio and can be split only by a chemical reaction, so carbon dioxide is always one carbon to two oxygens. Mixtures keep the properties of their parts and come apart physically, air by cooling and distilling, seawater by evaporation.

A ball is dropped from a rooftop. As it falls toward the ground,

• a.kinetic energy becomes potential energy
• b.potential energy becomes kinetic energy✓
• c.potential energy becomes chemical energy
• d.kinetic energy becomes thermal energy

Gravity does work on the falling ball, so the store that depends on height shrinks while its speed and kinetic energy grow, and the total stays nearly constant until air drag bleeds some off as heat. The reverse conversion is what happens on the way up, as a thrown ball slows while climbing.

Heat from the sun crosses the near-vacuum of space and reaches Earth by

• a.conduction
• b.radiation✓
• c.convection
• d.insulation

Radiation carries energy as electromagnetic waves and needs no matter at all, which is why sunlight can cross empty space. Conduction needs particles touching so vibrations pass along, and convection needs a fluid free to circulate, so neither works where there is nothing to carry the heat.

Which property of a sound wave determines how loud the sound is?

• a.its frequency
• b.its wave speed
• c.its amplitude✓
• d.its wavelength

Amplitude is how far the air particles swing from rest, and a bigger swing delivers more energy to the eardrum, so the sound is louder. Frequency tempts, but it sets pitch, how high or low the note is; wave speed is fixed by the medium, so shouting does not make sound arrive any sooner.

A glass prism splits white light into a band of colors because

• a.each color bends by a different amount✓
• b.all colors bend by the same amount
• c.the glass creates colors as light passes
• d.the prism reflects colors off its faces

White light is a mixture of wavelengths, and glass slows violet more than red, so each color refracts through a slightly different angle and the beam fans out into a spectrum. The prism adds nothing of its own: a second prism can bend the colors back together into plain white light.

A car brakes hard and an unbelted passenger is thrown toward the windshield. This is best explained by

• a.friction dragging the body along
• b.gravity pulling the body forward
• c.the body's inertia keeping it moving✓
• d.the seat pushing the body forward

Newton's first law says a body keeps its speed and direction unless an outside force acts, so the passenger keeps travelling at the car's old speed while the brakes slow the car. Nothing throws the passenger forward; a belt supplies the backward force that would stop them with the car.