Question Bank for Grade 8 Science

The atomic number of krypton is 36. If the mass number of a krypton atom is 84, which table shows the number of subatomic particles inside and outside the nucleus of the krypton atom?

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Atoms of which two elements have a combined total of 23 protons?

• Sodium, Na, and magnesium, Mg

• Boron, B, and carbon, C

• Copper, Cu, and zinc, Zn

• None of these

• Particle W

• Particle X

• Particle Y

• Particle Z

A student is trying to classify an unidentified, solid gray material as a metal or a nonmetal. Which question will best help the student classify the material?

• Is the material malleable or ductile?

• Does the material feel hard to the touch?

• Will the material float in water?

• Does the material feel rough or smooth?

• 4 carbon atoms, 11 hydrogen atoms, and 1 oxygen atom

• 7 carbon atoms, 14 hydrogen atoms, and 1 oxygen atom

• 7 carbon atoms, 11 hydrogen atoms, and 8 oxygen atoms

• 6 carbon atoms, 14 hydrogen atoms, and 3 oxygen atoms

Which statement best describes evidence that a chemical reaction occurs as a cake bakes?

• the water in the cake batter evaporates

• the cake rises as gas bubbles form in the baking cake

• the cake takes the shape of the container in which it is baked

• the water in the cake batter is used to keep the cake moist as it bakes

• the mother moves forward, and the daughter moves backward with a greater acceleration

• both move forward, but the mother moves with greater acceleration

• the mother moves backward, and the daughter moves forward with a greater acceleration

• both move backward, but the daughter moves with a greater acceleration

The diagrams show forces acting on a toy car as it moves to the right. Which diagram shows the toy car that will most likely accelerate to the right based on these conditions?

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A large rock is motionless on a flat sidewalk. Which statement best explains why the rock remains motionless?

• there are no forces acting on the rock

• the only force acting on the rock is directed toward the sidewalk

• the forces acting on the rock are all balanced

• the sidewalk exerts an unbalanced force on the rock

A pitcher throws a ball toward a player holding a softball bat. The player uses the bat to hit the ball. The bat applies a 10 newton force to the ball. Which statement correctly describes the reaction force between the bat and the ball?

• the reaction force is the force that causes the ball to move toward the bat

• the reaction force is the force applied to the bat by the player holding the bat

• the reaction force is the force that pulls the ball toward the ground

• the reaction force is the force of the ball on the bat