8th Grade Science Quiz
Questions: 16 · 10 minutes
1. Why does the Northern Hemisphere usually experience warmer temperatures in June than in December?
Earth is much closer to the Sun in June.
The Northern Hemisphere is tilted toward the Sun and receives more direct sunlight.
The Sun produces more energy during June.
Earth rotates more slowly in June, making each day warmer.
2. A solid sample has a mass of 24 grams and a volume of 8 cubic centimeters. What is its density, and what will it most likely do when placed in water with a density of 1 gram per cubic centimeter?
0.33 g/cm³, so it will sink
3 g/cm³, so it will float
32 g/cm³, so it will sink
3 g/cm³, so it will sink
3. What happens when a neutral atom gains one electron?
It becomes a negatively charged ion.
It becomes a positively charged ion.
Its atomic number increases by one.
Its nucleus loses one proton.
4. What type of rock forms when molten material cools and solidifies?
Metamorphic rock
Sedimentary rock
Igneous rock
Weathered rock
5. Water vapor touches a cool window and forms liquid droplets. Which process has occurred?
Evaporation
Precipitation
Condensation
Sublimation
6. A standing passenger lurches forward when a bus stops suddenly. Which explanation best applies?
Gravity briefly pulls the passenger toward the front of the bus.
The passenger's body tends to keep moving because of inertia.
The stopping bus creates a forward magnetic force.
The passenger gains mass as the bus slows down.
7. Three identical bulbs are connected in parallel to a battery. One bulb is removed without breaking the other branches. What will most likely happen?
All remaining bulbs will go out because the circuit is open everywhere.
The battery will immediately reverse its positive and negative terminals.
The other bulbs will remain lit because each has its own path.
The other bulbs will become part of a single series circuit automatically.
8. What is the main function of the cell membrane?
It assembles the cell's chromosomes during reproduction.
It stores most of the cell's genetic information.
It releases all of the cell's energy directly from sunlight.
It regulates which substances enter and leave the cell.
9. A few insects in a population are naturally resistant to a pesticide. After repeated pesticide use, resistant insects become more common. Which process best explains this change?
Each insect deliberately developed resistance when exposed.
The pesticide caused every insect to produce identical mutations.
Nonresistant insects changed species before reproducing.
Resistant insects survived and passed their traits to more offspring.
10. A student slowly adds pure water to an acidic solution with a pH of 3. What will most likely happen to the solution's pH?
It will fall below 3 because the volume increases.
It will remain exactly 3 because water cannot affect pH.
It will rise toward 7 as the acid becomes more dilute.
It will immediately become exactly 7 after the first drop.
11. In pea plants, B represents a dominant allele and b represents a recessive allele. If a Bb plant is crossed with a bb plant, what is the probability that an offspring will have the bb genotype?
50%
25%
75%
100%
12. Which observation provides the strongest evidence that a chemical change has occurred?
Ice melts into liquid water.
Two clear liquids are mixed and produce bubbles of a new gas.
Sugar disappears as it dissolves in water.
A metal wire is bent into a new shape.
13. A skateboarder moves in a straight line at constant velocity. A 10-newton force pushes forward while another 10-newton force pushes backward. What does this show?
The net force is zero, so the motion does not have to change.
The skateboarder must stop because the backward force cancels all motion.
The skateboarder's speed must increase because two forces are acting.
The net force is 20 newtons in the forward direction.
14. Two tectonic plates move away from each other beneath an ocean. What is most likely to occur at their boundary?
One plate is forced beneath the other, forming a deep-ocean trench.
Magma rises and cools, creating new oceanic crust.
Both plates stop moving as their edges lock permanently.
Continental crust folds upward without any magma reaching the surface.
15. In the food chain grass → rabbit → fox, a disease greatly reduces the amount of grass. What is the most likely short-term effect on the rabbit population?
It will decrease because less food energy is available.
It will remain unchanged because rabbits are consumers.
It will increase because foxes will eat more grass.
It will become a producer to replace the missing grass.
16. A student tests whether the amount of sunlight affects how tall bean plants grow. The plants receive different amounts of sunlight, while their soil, water, and containers remain the same. What is the independent variable?
The amount of water given to each plant
The type and amount of soil used
The height reached by each plant
The amount of sunlight each plant receives