Physical Science (Grade 8) Midterm — Units 3–4

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Science Grade 8 20 multiple choice + 1 written

Free printable Physical Science midterm (Grade 8): 20 multiple-choice questions plus 1 written response covering Chemical Reactions, Forces & Motion. Answer key included — customize it in the Midterm Maker.

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Directions: Read each question carefully and choose the best answer. Answer the written response in complete sentences.

Covers: Chemical Reactions · Forces & Motion

Part 1: Multiple Choice

How many hydrogen atoms are shown in 2H₂O?
1. A. 2
2. B. 6
3. C. 4
4. D. 3
Increasing the temperature of reactants usually has what effect on reaction rate?
1. A. It slows down the reaction
2. B. It has no effect
3. C. It stops the reaction
4. D. It speeds up the reaction
Which coefficients balance the equation ___ H₂ + ___ O₂ → ___ H₂O?
1. A. 2, 1, 2
2. B. 2, 2, 1
3. C. 1, 2, 2
4. D. 1, 1, 1
A reaction that releases heat to its surroundings is called what?
1. A. Endothermic
2. B. Exothermic
3. C. Physical
4. D. Neutral
In a sealed container, 12 g of substance A reacts completely with 8 g of substance B. What is the total mass of the products?
1. A. 4 g
2. B. 12 g
3. C. 20 g
4. D. 96 g
What does a catalyst do in a chemical reaction?
1. A. Speeds up the reaction without being used up
2. B. Becomes one of the products
3. C. Slows the reaction and is used up
4. D. Adds mass to the products
In a chemical reaction, what are the starting substances called?
1. A. Products
2. B. Catalysts
3. C. Reactants
4. D. Solutions
A solution has a pH of 2. How is it best described?
1. A. Neutral
2. B. Strongly basic
3. C. Weakly basic
4. D. Strongly acidic
Which observation is the best evidence that a chemical reaction occurred?
1. A. An ice cube melts
2. B. Gas bubbles form when baking soda and vinegar mix
3. C. Sugar dissolves in water
4. D. A glass cup breaks
What does the law of conservation of mass state?
1. A. Mass is destroyed when gases form
2. B. Mass is not created or destroyed in a chemical reaction
3. C. Products always weigh more than reactants
4. D. Reactants always weigh more than products
How is velocity different from speed?
1. A. Velocity is measured in newtons
2. B. Velocity ignores distance
3. C. Velocity includes direction
4. D. Velocity is always faster
Two teams pull on a rope with equal force in opposite directions. What happens to the rope?
1. A. It moves with twice the force
2. B. It speeds up toward one team
3. C. It accelerates straight upward
4. D. It does not accelerate because the net force is zero
An astronaut travels from Earth to the Moon. What happens to her mass and weight?
1. A. Her mass decreases, but her weight stays the same
2. B. Her mass stays the same, but her weight decreases
3. C. Her mass and weight both stay the same
4. D. Her mass and weight both decrease
What is the SI unit of force?
1. A. Watt
2. B. Joule
3. C. Kilogram
4. D. Newton
A car travels 150 km in 3 hours. What is its average speed?
1. A. 450 km/h
2. B. 30 km/h
3. C. 50 km/h
4. D. 153 km/h
Which statement describes Newton's first law of motion?
1. A. An object keeps its motion unless an unbalanced force acts on it
2. B. Force equals mass times acceleration
3. C. Heavier objects always fall faster
4. D. Every action has an equal and opposite reaction
A swimmer pushes water backward and moves forward. Which law does this show?
1. A. Newton's second law
2. B. Newton's first law
3. C. Newton's third law
4. D. The law of conservation of mass
A car speeds up from 0 m/s to 20 m/s in 4 seconds. What is its acceleration?
1. A. 5 m/s²
2. B. 24 m/s²
3. C. 16 m/s²
4. D. 80 m/s²
Which force opposes motion between two surfaces that are touching?
1. A. Magnetism
2. B. Gravity
3. C. Buoyancy
4. D. Friction
What net force is needed to accelerate a 10 kg cart at 2 m/s²?
1. A. 5 N
2. B. 8 N
3. C. 12 N
4. D. 20 N

Part 2: Written Response

Using Newton's three laws of motion, explain what happens to a soccer ball from the moment it is kicked until it stops rolling.

Answer Key — Physical Science (Grade 8) Midterm — Units 3–4

C — 4 Each H₂O has 2 hydrogen atoms; 2 × 2 = 4.
D — It speeds up the reaction Faster particles collide more often and with more energy.
A — 2, 1, 2 2H₂ + O₂ → 2H₂O gives 4 H and 2 O on each side.
B — Exothermic Exo- means 'out'; energy flows out as heat.
C — 20 g Mass is conserved: 12 g + 8 g = 20 g.
A — Speeds up the reaction without being used up Catalysts lower the energy needed for a reaction to start.
C — Reactants Reactants are on the left side of the arrow.
D — Strongly acidic pH below 7 is acidic; 2 is strongly acidic.
B — Gas bubbles form when baking soda and vinegar mix Formation of a new gas signals a new substance.
B — Mass is not created or destroyed in a chemical reaction Atoms are rearranged, so total mass stays the same.
C — Velocity includes direction Velocity is speed in a given direction.
D — It does not accelerate because the net force is zero Balanced forces cause no change in motion.
B — Her mass stays the same, but her weight decreases Mass is amount of matter; weight depends on gravity.
D — Newton Force is measured in newtons (N).
C — 50 km/h Speed = distance ÷ time = 150 ÷ 3 = 50 km/h.
A — An object keeps its motion unless an unbalanced force acts on it The first law is the law of inertia.
C — Newton's third law The water pushes back on the swimmer with an equal, opposite force.
A — 5 m/s² a = change in velocity ÷ time = 20 ÷ 4 = 5 m/s².
D — Friction Friction acts opposite to the direction of sliding.
D — 20 N F = m × a = 10 × 2 = 20 N.

Written Response — Look-Fors

First law: ball stays at rest until kicked, slows due to friction; second law: harder kick/greater force gives greater acceleration (F = ma); third law: ball pushes back on foot.

Physical Science (Grade 8) Midterm — Units 3–4

Part 1: Multiple Choice

Part 2: Written Response

Written Response — Look-Fors

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