general science

2. The layer of the Earth's atmosphere where most weather phenomena occur.
4. The smallest unit of an element, consisting of protons, neutrons, and electrons.
7. The study of heredity and genetic variation.
8. The ability of an object to float in a liquid.
9. A unit of pressure equal to one newton per square meter.
11. The study of the relationships between organisms and their environment.
14. The study of the behavior and properties of light.
15. The curved path followed by a celestial object around a more massive object due to gravity.
16. The process of two or more atomic nuclei combining to form a heavier nucleus.
18. The process of a gas turning into a plasma due to extreme heat.
19. A process of nuclear decay where an atomic nucleus emits an alpha particle.

1. A measure of how acidic or basic a substance is.
3. The region in the Earth's atmosphere where ozone absorbs most of the Sun's ultraviolet radiation.
5. The study of the Earth's past geological periods based on fossils and rock layers.
6. The process by which a substance changes directly from a gas to a solid, bypassing the liquid state.
9. A fundamental particle that carries the electromagnetic force and forms photons
10. The attractive force between two masses that depends on their masses and the distance between them.
12. The study of the universe's origin, evolution, and eventual fate.
13. The energy an object possesses due to its motion.
17. The densest planet in our solar system.