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DC CAPE 2.0 Science Grade 8 study materials
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DC CAPE 2.0 Science Grade 8 practice questions

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Question 1Matter and Its Interactions

Which statement best describes what happens to the particles of a substance as it changes from a liquid to a gas?

  1. The particles break apart into smaller atoms.
  2. The particles shrink in size but keep the same spacing.
  3. The particles lose energy and become fixed in a rigid pattern.
  4. The particles gain energy and move farther apart from one another. Correct answer.

Explanation

Vaporization adds energy, so particles overcome attractions and spread out into the gas state. Particle size and identity do not change during a phase change. Spacing increases rather than staying the same.

Question 2Matter and Its Interactions

A sealed jar contains 40 grams of a solid that reacts completely with a gas to form a new solid. The jar is closed the entire time. What is the total mass of everything in the jar after the reaction?

  1. Exactly 40 grams, because mass is conserved in a closed system. Correct answer.
  2. Less than 40 grams, because a gas was used up.
  3. More than 40 grams, because a new substance formed.
  4. It cannot be predicted without knowing the gas.

Explanation

The law of conservation of mass states that total mass stays constant in a closed system because atoms are only rearranged. No matter enters or leaves the sealed jar. Therefore the total mass after reaction equals the mass before.

Question 3Matter and Its Interactions

Which of these is the best description of an atom?

  1. A particle made only of protons.
  2. The smallest unit of an element that keeps the element's properties. Correct answer.
  3. The smallest particle of a compound.
  4. A mixture of two or more elements.

Explanation

An atom is the smallest unit of an element that still has that element's chemical properties. It contains protons, neutrons, and electrons. Atoms can combine to form compounds but are not themselves compounds or mixtures.

Question 4Matter and Its Interactions

A student stirs sugar into water until no crystals remain and the liquid looks clear. Which term best describes the resulting liquid?

  1. A heterogeneous mixture
  2. A suspension
  3. A solution Correct answer.
  4. A compound

Explanation

A solution is a homogeneous mixture in which one substance is dissolved evenly in another. Clear, evenly mixed sugar water fits this definition. A compound would require a chemical reaction forming new bonds.

Question 5Matter and Its Interactions

Which change is a chemical change rather than a physical change?

  1. Paper being torn into strips
  2. Ice melting into liquid water
  3. Salt dissolving in water
  4. A piece of iron rusting Correct answer.

Explanation

A chemical change produces a new substance with different properties. Rust is a new compound formed from iron, oxygen, and water. Melting, dissolving, and tearing only change form or arrangement.

Question 6Matter and Its Interactions

In a neutral atom of carbon-12, how many electrons are present?

  1. 18
  2. 6 Correct answer.
  3. 12
  4. 4

Explanation

A neutral atom has equal numbers of protons and electrons. Carbon's atomic number is 6, so it has 6 protons and 6 electrons. The mass number 12 reflects protons plus neutrons, not electrons.

Question 7Matter and Its Interactions

Which statement correctly compares the spacing of particles in a gas with the spacing in a liquid?

  1. Gas and liquid particles are spaced equally.
  2. Gas particles are much farther apart than liquid particles. Correct answer.
  3. Gas particles are packed closer together than liquid particles.
  4. Gas particles touch each other but liquid particles do not.

Explanation

Gas particles are far apart with mostly empty space between them, which lets gases be compressed. Liquid particles are close together but able to slide past one another. This difference in spacing explains many property differences.

Question 8Matter and Its Interactions

A substance has a fixed volume but takes the shape of its container. In which state of matter is the substance?

  1. Gas
  2. Liquid Correct answer.
  3. Plasma
  4. Solid

Explanation

A liquid has a definite volume because its particles stay close together, but it flows to match its container's shape. Solids have fixed shape and volume, and gases fill the whole container.

Question 9Matter and Its Interactions

A balloon is placed in a freezer and shrinks. Which statement best explains this observation?

  1. The balloon material absorbs the gas.
  2. Gas particles move more slowly and occupy less space at lower temperature. Correct answer.
  3. Gas particles combine chemically to form a liquid inside the balloon.
  4. Gas particles are destroyed by the cold.

Explanation

Cooling removes kinetic energy, so gas particles move more slowly and collide with less force, allowing the volume to decrease at constant pressure. The particles themselves are not destroyed or absorbed. The change is physical, not a chemical combination.

Question 10Matter and Its Interactions

Which observation provides the strongest evidence that a chemical reaction has occurred?

  1. A new gas forms with a distinct odor while the mixture warms. Correct answer.
  2. A solid is ground into a fine powder.
  3. A colored crystal is added to water and the color spreads.
  4. A clear liquid is heated until it boils.

Explanation

Formation of a new gas, a temperature change, and a new odor are signs that new substances were produced. Grinding and dissolving are physical changes that keep the same substances. Boiling is a phase change.

Question 11Matter and Its Interactions

A compound contains 6 g of element X combined with 24 g of element Y. What is the ratio of the mass of X to the mass of Y in this compound?

  1. 6:1
  2. 1:6
  3. 4:1
  4. 1:4 Correct answer.

Explanation

The mass ratio is found by dividing the mass of X by the mass of Y: 6 g to 24 g simplifies to 1:4. A fixed compound always has the same mass ratio of its elements. The other choices invert the ratio or use unrelated numbers.

Question 12Matter and Its Interactions

Two samples of the same pure compound are tested. Sample A has a mass of 10 g and Sample B has a mass of 30 g. Which statement about the percent composition by mass is correct?

  1. The percent composition depends on how the samples were prepared.
  2. Sample A has a higher percent composition because it is smaller.
  3. Both samples have the same percent composition by mass. Correct answer.
  4. Sample B has a higher percent of each element because it is larger.

Explanation

A pure compound has a fixed composition by mass, so percent composition is the same no matter the sample size. Doubling the mass doubles each element's mass proportionally. Percent composition is an intensive property.

Question 13Matter and Its Interactions

In the chemical formula H2O, what does the subscript 2 indicate?

  1. There are two oxygen atoms in each molecule.
  2. There are two water molecules present.
  3. The molecule has a charge of +2.
  4. There are two hydrogen atoms in each molecule. Correct answer.

Explanation

A subscript counts atoms of the element just before it, so H2 means two hydrogen atoms per molecule. The absence of a subscript after O means one oxygen atom. Subscripts describe atom counts, not molecule counts or charge.

Question 14Matter and Its Interactions

Which statement correctly describes how a physical mixture differs from a compound?

  1. A compound can be separated by filtering, while a mixture cannot.
  2. A mixture is always a single pure substance.
  3. A mixture can be separated by physical means, while a compound requires a chemical change. Correct answer.
  4. A mixture has a fixed ratio of parts, while a compound does not.

Explanation

Mixtures keep the properties of their components and can be separated physically, such as by filtering or evaporation. Compounds form through chemical bonding and require chemical reactions to break apart. Their ratios are fixed, unlike mixtures.

Question 15Matter and Its Interactions

A sample of matter is heated and its temperature rises steadily, then stays constant for several minutes while it is still being heated. What is most likely happening during the constant-temperature period?

  1. The thermometer has stopped working.
  2. The substance is gaining no energy at all.
  3. A phase change is occurring, and energy is breaking particle attractions. Correct answer.
  4. The substance is chemically decomposing into new elements.

Explanation

During a phase change, added energy goes into overcoming attractions between particles rather than raising temperature. That is why the temperature plateaus even while heat is supplied. Once the change completes, the temperature rises again.

Question 16Matter and Its Interactions

Which of the following best explains why gases can be compressed into a smaller volume more easily than liquids?

  1. Liquid particles are heavier than gas particles.
  2. Gas particles have large empty spaces between them, while liquid particles are close together. Correct answer.
  3. Gas particles are softer than liquid particles.
  4. Gas particles attract each other more strongly than liquid particles.

Explanation

Compressibility depends on how much empty space exists between particles. Gases have mostly empty space, so pushing particles closer is easy. Liquids are already closely packed, leaving little room to compress.

Question 17Matter and Its Interactions

A student dissolves 5 g of salt in 95 g of water. What is the mass percent of salt in the solution?

  1. 5.3%
  2. 5.0% Correct answer.
  3. 95%
  4. 10%

Explanation

Mass percent equals the mass of solute divided by the total mass of solution, times 100. Here 5 g divided by 100 g equals 0.05, or 5.0%. The total mass is the solute plus the solvent.

Question 18Matter and Its Interactions

An atom of an element has 11 protons, 12 neutrons, and 11 electrons. Which statement about this atom is correct?

  1. It has a net charge of +1.
  2. Its mass number is 23. Correct answer.
  3. Its atomic number is 23.
  4. Its mass number is 11.

Explanation

Mass number equals protons plus neutrons, so 11 + 12 = 23. Atomic number equals the number of protons, which is 11. With 11 protons and 11 electrons, the atom is neutral.

Question 19Matter and Its Interactions

Which statement about the law of conservation of mass is correct?

  1. The total mass of reactants equals the total mass of products in a closed system. Correct answer.
  2. Mass is conserved only in physical changes, not chemical reactions.
  3. Mass is created when a gas is produced in a reaction.
  4. Mass is lost whenever a solid dissolves in a liquid.

Explanation

The law of conservation of mass applies to both physical and chemical changes: atoms are rearranged, never created or destroyed. In a closed system, reactant mass equals product mass. Escaped gases can make mass appear lost in open systems.

Question 20Matter and Its Interactions

A chemist reacts 12 g of carbon with oxygen to produce 44 g of carbon dioxide. What mass of oxygen reacted?

  1. 32 g Correct answer.
  2. 56 g
  3. 44 g
  4. 12 g

Explanation

By conservation of mass, the mass of reactants equals the mass of products. The oxygen mass equals 44 g minus 12 g, which is 32 g. Adding the reactant masses confirms 12 g + 32 g = 44 g.

Question 21Matter and Its Interactions

Two clear liquids are mixed in a beaker. A solid suddenly appears, and the beaker feels warmer. Which conclusion is best supported?

  1. A physical change occurred because the liquids are still clear.
  2. The solid is simply undissolved liquid that froze.
  3. No change occurred because no gas was produced.
  4. A chemical reaction occurred, forming a new solid and releasing energy. Correct answer.

Explanation

Formation of a solid from two clear liquids (a precipitate) plus a temperature rise are strong signs of a chemical reaction. New substances formed, and energy was released. Physical changes do not create a new solid from dissolved reactants.

Question 22Matter and Its Interactions

A pure substance melts at exactly 0 °C and boils at exactly 100 °C at standard pressure. Which substance is this most likely to be?

  1. Rubbing alcohol
  2. Pure water Correct answer.
  3. A sugar solution
  4. Salt water

Explanation

Pure water has a melting point of 0 °C and a boiling point of 100 °C at standard pressure. Dissolved substances raise the boiling point and lower the melting point. Fixed sharp melting and boiling points indicate a pure substance.

Question 23Matter and Its Interactions

A sample of a compound is found to contain 40% calcium, 12% carbon, and 48% oxygen by mass. If a second sample of the same compound has a mass of 200 g, what mass of carbon does it contain?

  1. 24 g Correct answer.
  2. 48 g
  3. 40 g
  4. 12 g

Explanation

Percent composition is fixed for a pure compound, so the carbon fraction is 12%. Twelve percent of 200 g is 0.12 × 200 = 24 g. The other values come from misapplying the percentages or the sample mass.

Question 24Matter and Its Interactions

A sealed container holds a mixture of ice and liquid water at 0 °C. Heat is slowly added until all the ice melts, and the temperature stays at 0 °C throughout. Which statement best explains why the temperature does not rise?

  1. The thermometer cannot detect small temperature changes in ice water.
  2. The water absorbs no energy while ice is present.
  3. The added energy breaks attractions between particles as ice changes to liquid. Correct answer.
  4. The added energy increases the average kinetic energy of the particles immediately.

Explanation

During melting, added energy is used to overcome attractions holding particles in the solid lattice rather than increasing average kinetic energy. Temperature measures average kinetic energy, so it stays constant until melting finishes. After all ice melts, added energy raises the temperature.

Question 25Matter and Its Interactions

An atom has 17 protons and 18 neutrons. A second atom has 17 protons and 20 neutrons. Which statement about these two atoms is correct?

  1. They are the same element and are isotopes of each other. Correct answer.
  2. They are different elements because their masses differ.
  3. They must have different chemical properties because their neutron counts differ.
  4. They have different atomic numbers.

Explanation

The element is determined by the number of protons, which is 17 for both atoms, so both are chlorine. Atoms of the same element with different neutron counts are isotopes. Their chemical behavior is essentially the same because the electron arrangement is unchanged.

Question 26Matter and Its Interactions

Which subatomic particle determines the identity of an element?

  1. The proton Correct answer.
  2. The electron
  3. The photon
  4. The neutron

Explanation

The number of protons in the nucleus (the atomic number) defines which element an atom is. Changing the proton count changes the element entirely, while changing neutrons or electrons does not.

Question 27Matter and Its Interactions

A solid ionic compound such as table salt conducts electricity when melted but not when solid. Which statement best explains this?

  1. In the solid state the ions are locked in place, but when melted the ions are free to move. Correct answer.
  2. Melting converts the ions into electrons, which carry the current.
  3. Melting destroys the ions, releasing charged particles into the air.
  4. The solid form contains no charged particles at all until it is heated.

Explanation

Electrical conduction requires mobile charged particles. In a solid ionic lattice the ions vibrate in fixed positions, but melting frees them to move and carry charge.

Question 28Matter and Its Interactions

A student heats a sample of a pure solid and records its temperature every minute. During melting, the temperature stays the same even though heating continues. What happens to the added energy?

  1. It is stored as potential energy that separates the particles. Correct answer.
  2. It is destroyed because the temperature does not change.
  3. It is converted into extra kinetic energy, raising the temperature slowly.
  4. It is lost to the surroundings, so the sample cannot gain heat.

Explanation

During a phase change, added energy overcomes the attractions between particles rather than increasing their average kinetic energy. Because temperature measures average kinetic energy, it stays constant until melting is complete.

Question 29Matter and Its Interactions

Which change of state involves a substance gaining thermal energy?

  1. Condensation
  2. Freezing
  3. Deposition
  4. Sublimation Correct answer.

Explanation

Sublimation is a solid changing directly to a gas, which requires absorbing energy to overcome particle attractions. Condensation, freezing, and deposition all release energy as particles come closer together.

Question 30Matter and Its Interactions

Element Q has an atomic number of 8 and a mass number of 16. How many neutrons are in one atom of Q?

  1. 24
  2. 8 Correct answer.
  3. 16
  4. 6

Explanation

The mass number equals protons plus neutrons, and the atomic number equals protons. Subtracting 8 protons from a mass number of 16 leaves 8 neutrons.

Question 31Matter and Its Interactions

A student mixes two clear solutions and observes bubbles forming rapidly while the mixture becomes warm. Which conclusion is best supported?

  1. A chemical reaction produced a gas and released energy. Correct answer.
  2. The bubbles are air that was dissolved in the water.
  3. The warmth came from the container absorbing heat.
  4. The solutions underwent only a physical change.

Explanation

Rapid bubbling plus a temperature rise indicates a new gas is formed and energy is released, both signs of a chemical change. Physical mixing of two liquids alone would not produce a new gas and release heat.

Question 32Matter and Its Interactions

An atom of an element has 12 protons, 12 neutrons, and 10 electrons. What is the charge of this particle?

  1. +10
  2. +2 Correct answer.
  3. 0
  4. -2

Explanation

Charge equals protons minus electrons. With 12 protons and 10 electrons, the particle has two more positive charges than negative charges, giving a charge of +2.

Question 33Matter and Its Interactions

Which statement best describes what happens to particles when a gas is cooled and condenses into a liquid?

  1. They stop moving completely.
  2. They lose kinetic energy and become held closer together by attractions. Correct answer.
  3. They gain kinetic energy and move farther apart.
  4. They break apart into smaller atoms.

Explanation

Cooling removes thermal energy, so the particles move more slowly and attractions can pull them into the closer arrangement of a liquid. The particles themselves are not broken apart during a phase change.

Question 34Matter and Its Interactions

Two atoms have the same number of electrons but different numbers of protons. Which statement about these atoms is correct?

  1. They must have identical mass numbers.
  2. They are isotopes of the same element because their electrons match.
  3. They are the same element with different charges only.
  4. They belong to different elements because their proton counts differ. Correct answer.

Explanation

Element identity is set by the number of protons (atomic number). Atoms with equal electrons but different protons are different elements, even if they share the same electron count.

Question 35Matter and Its Interactions

A compound is made of element A and element B. In one sample the mass of A is twice the mass of B. A second sample of the same compound has 8 g of A. According to the law of definite proportions, what mass of B should the second sample contain?

  1. 2 g
  2. 4 g Correct answer.
  3. 8 g
  4. 16 g

Explanation

The law of definite proportions states that a compound always contains its elements in the same mass ratio. If A is twice B by mass, then 8 g of A pairs with 4 g of B.

Question 36Matter and Its Interactions

Which statement best explains why a sugar cube dissolves faster when it is crushed into fine powder?

  1. Crushing increases the surface area exposed to the solvent. Correct answer.
  2. Crushing increases the temperature of the sugar.
  3. Crushing changes the sugar into a different compound.
  4. Crushing increases the mass of the sugar.

Explanation

Dissolving happens at the surface where solvent contacts solute. Crushing a solid exposes more surface area, so more particles can dissolve per unit of time.

Question 37Matter and Its Interactions

A sealed flask contains a mixture of hydrogen and oxygen gases at room temperature. No reaction occurs until a spark is added. Which statement best explains why the gases do not react on their own?

  1. The particles lack enough energy to overcome the activation barrier until the spark provides it. Correct answer.
  2. The flask walls prevent the particles from colliding.
  3. The gases cannot react because they are in the same container.
  4. Hydrogen and oxygen never react with each other.

Explanation

Reacting molecules must collide with enough energy to break bonds and start the reaction. At room temperature few collisions have that energy, but a spark supplies the needed activation energy.

Question 38Matter and Its Interactions

A sample of a compound is analyzed and found to contain 40% sulfur and 60% oxygen by mass. A second sample of the same compound is found to contain 20 g of sulfur. What mass of oxygen should the second sample contain?

  1. 40 g
  2. 30 g Correct answer.
  3. 20 g
  4. 60 g

Explanation

The compound always has the same mass ratio, here 40 parts sulfur to 60 parts oxygen, or 2:3. If the sulfur mass is 20 g, the oxygen mass must be 30 g to keep the 2:3 ratio.

Question 39Matter and Its Interactions

In a closed container, 4 g of hydrogen reacts completely with 32 g of oxygen to form water, with no gas left over. Which mass of water is produced?

  1. 4 g
  2. 36 g Correct answer.
  3. 28 g
  4. 32 g

Explanation

The law of conservation of mass states that total mass is unchanged in a chemical reaction. Adding the reacting masses, 4 g plus 32 g, gives 36 g of water.

Question 40Matter and Its Interactions

A student claims that when a liquid evaporates in an open cup, the particles that leave are the fastest-moving ones. Which observation best supports this claim?

  1. Evaporation happens more quickly when the liquid is warmed.
  2. The liquid's total mass decreases over time.
  3. The remaining liquid cools slightly as evaporation proceeds. Correct answer.
  4. Evaporation happens more slowly when the surface area is reduced.

Explanation

The particles that escape are the ones with the most kinetic energy. Removing high-energy particles lowers the average kinetic energy of those left behind, which shows up as cooling.

Question 41Motion and Stability: Forces and Interactions

A student pushes a book across a table at a constant speed. Which statement best describes the forces acting on the book?

  1. Friction is larger than the applied force, so the book slows down.
  2. No forces act on the book because it moves at a steady speed.
  3. The applied force is larger than friction, so the book speeds up.
  4. The applied force is balanced by friction, so the net force is zero. Correct answer.

Explanation

An object moving at constant velocity has zero acceleration, so the net force on it must be zero. The push forward and friction backward must be equal in size and opposite in direction.

Question 42Motion and Stability: Forces and Interactions

Which unit is used to measure force in the SI system?

  1. watt
  2. joule
  3. pascal
  4. newton Correct answer.

Explanation

Force is measured in newtons (N), where one newton is the force that accelerates a 1 kg mass at 1 m/s². The other units measure energy, power, and pressure.

Question 43Motion and Stability: Forces and Interactions

Two students push a box in the same direction, one with 30 N and the other with 20 N. What is the size of the net force on the box?

  1. 25 N
  2. 600 N
  3. 10 N
  4. 50 N Correct answer.

Explanation

Forces acting in the same direction add together, so the net force is 30 N + 20 N = 50 N. The net force points in the direction both students push.

Question 44Motion and Stability: Forces and Interactions

A book rests on a table without moving. Which pair of forces is balanced in this situation?

  1. The book's weight and friction along the table
  2. The book's weight and the book's push on the table
  3. The book's weight and the normal force from the table Correct answer.
  4. The normal force and the table's weight

Explanation

The book is at rest, so the forces on the book must balance. Earth pulls the book down with its weight while the table pushes up with a normal force of equal size.

Question 45Motion and Stability: Forces and Interactions

Which statement best describes inertia?

  1. The tendency of an object to resist changes in its motion Correct answer.
  2. The force that pulls objects toward Earth
  3. The speed an object reaches when falling
  4. The friction between two surfaces in contact

Explanation

Inertia is an object's resistance to any change in its state of motion, and it depends on mass. A more massive object is harder to start or stop moving.

Question 46Motion and Stability: Forces and Interactions

A wagon is pulled with a net force of 40 N and has a mass of 8 kg. What is its acceleration?

  1. 0.2 m/s²
  2. 32 m/s²
  3. 5 m/s² Correct answer.
  4. 320 m/s²

Explanation

Newton's second law states that acceleration equals net force divided by mass (a = F/m). Dividing 40 N by 8 kg gives 5 m/s².

Question 47Motion and Stability: Forces and Interactions

A soccer ball is kicked and rolls across the grass until it stops. Which force most directly causes the ball to slow down?

  1. Gravity pulling the ball downward
  2. The normal force from the ground
  3. Friction between the ball and the grass Correct answer.
  4. Air pressure inside the ball

Explanation

Friction acts opposite the ball's motion along the surface, producing a net force that reduces its speed. Without friction the ball would keep rolling at constant velocity.

Question 48Motion and Stability: Forces and Interactions

A passenger in a car lurches forward when the driver suddenly brakes. Which principle best explains this?

  1. Objects at rest tend to stay at rest unless acted on by a force
  2. Every action has an equal and opposite reaction
  3. Force equals mass times acceleration
  4. An object in motion tends to stay in motion unless acted on by a force Correct answer.

Explanation

The passenger is already moving with the car, and when the car brakes, the passenger's body tends to keep moving forward. This is inertia of motion described by Newton's first law.

Question 49Motion and Stability: Forces and Interactions

A crate has a mass of 10 kg. Using g = 9.8 m/s², what is the weight of the crate?

  1. 980 N
  2. 98 N Correct answer.
  3. 0.98 N
  4. 9.8 N

Explanation

Weight is the gravitational force on an object, calculated as W = mg. Multiplying 10 kg by 9.8 m/s² gives 98 N.

Question 50Motion and Stability: Forces and Interactions

Which statement correctly distinguishes mass from weight?

  1. Mass and weight are both measured in newtons.
  2. Mass is a measure of matter, while weight is the gravitational force on that matter. Correct answer.
  3. Mass changes with location, but weight stays the same.
  4. Weight is the amount of matter, while mass is a force.

Explanation

Mass measures the amount of matter and does not change with location, while weight is the force of gravity acting on that mass and depends on the local gravitational field. Mass is measured in kilograms and weight in newtons.