ASVAB General Science: What's on It and the Facts to Know

What the subtest is

The official ASVAB site describes General Science as knowledge of the physical and biological sciences. It's the first subtest on the computer test (CAT-ASVAB):

GS doesn't count toward your AFQT, the score that decides basic eligibility. It counts toward jobs. The Air Force lists its Electronics composite as Arithmetic Reasoning, Electronics Information, General Science, and Mathematics Knowledge. Each service sets its own composites, so ask your recruiter which subtests count for the jobs you want. The line scores guide explains how composites work.

The official description is one line, so no public outline lists every topic. The fact sheet below covers the basics of each major science area, the level a broad high-school science test is built on.

Life science

From OpenStax Biology:

Plant cells have a cell wall, chloroplasts, and a large central vacuole that animal cells lack.

The heart has four chambers: two atria and two ventricles. The right side pumps blood to the lungs, and the left side pumps it to the rest of the body. Arteries carry blood away from the heart and veins carry it back. Capillaries are where oxygen, nutrients, and wastes are exchanged with the tissues.

Chemistry

From OpenStax Chemistry:

• An atom's nucleus holds protons (positive charge) and neutrons (no charge). Electrons (negative charge) are outside the nucleus.
• The atomic number is the number of protons, and it identifies the element.
• The mass number is protons plus neutrons.
• Isotopes of an element have the same number of protons but different numbers of neutrons. Magnesium-24 and magnesium-26 are both magnesium.

Earth science

From the U.S. Geological Survey, Earth's layers from the outside in:

A common trap: the outer core is liquid and the inner core is solid, not the other way around.

Astronomy

From NASA, the eight planets in order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

• Mercury, Venus, Earth, and Mars are the rocky terrestrial planets.
• Jupiter and Saturn are gas giants; Uranus and Neptune are ice giants.
• Pluto was reclassified as a dwarf planet in 2006 by the International Astronomical Union.

Physical science

Physics on GS overlaps with two other subtests. Electricity basics, such as Ohm's law, are in the Electronics Information guide, and forces, levers, and pulleys are in the Mechanical Comprehension guide. Studying those helps GS too.

Check yourself

1. Which organelle makes most of a cell's ATP? Mitochondria.
2. An atom has 8 protons and 8 neutrons. What's its atomic number? 8; the neutrons only affect the mass number, which is 16.
3. Which layer of Earth is liquid? The outer core.
4. Which side of the heart pumps blood to the lungs? The right side.

How to study GS

• Short and daily. Fifteen minutes of facts a day beats one long cram session for a broad, recall-heavy subtest.
• Use your misses. Each wrong answer names a fact to add to your review list.
• Don't overspend. If your recruiter says GS doesn't count for the jobs you want, put the time into the AFQT subtests first. The study guide shows how to split the time.

Practice ASVAB General Science questions with explanations → to find the science areas you still miss.