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GA Milestones Science Grade 8 study materials
GA Milestones Science Grade 8 study resources

GA Milestones Science Grade 8 practice questions

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Question 1Science

A student heats a beaker of water on a hot plate. Which statement best describes what happens to the water molecules as the temperature rises?

  1. The molecules become larger because heat adds mass to each particle.
  2. The molecules change into a different element at higher temperatures.
  3. The molecules stop moving so that the water can absorb energy.
  4. The molecules move faster because their average kinetic energy increases. Correct answer.

Explanation

Temperature is a measure of the average kinetic energy of particles, so adding thermal energy makes the molecules move faster. The particles themselves do not gain mass or change into different elements during ordinary heating.

Question 2Science

A marble is dropped from a table and falls to the floor. Ignoring air resistance, how does the energy of the marble change as it falls?

  1. Potential energy increases while kinetic energy decreases.
  2. Potential energy decreases while kinetic energy increases. Correct answer.
  3. Both potential and kinetic energy stay constant during the fall.
  4. Both potential and kinetic energy decrease to zero.

Explanation

As the marble falls, its height above the floor decreases, so gravitational potential energy is converted into kinetic energy. Its speed increases, which is why kinetic energy rises while total mechanical energy stays constant when friction is ignored.

Question 3Science

Which statement correctly compares a compound with a mixture?

  1. A compound can be separated by filtering, while a mixture cannot.
  2. A compound contains only one type of atom, while a mixture contains several types.
  3. A compound has variable composition, while a mixture has fixed composition.
  4. A compound is made of elements chemically bonded in fixed ratios, while a mixture is physically combined. Correct answer.

Explanation

In a compound, atoms of different elements are chemically bonded in a definite ratio, and separating them requires a chemical change. A mixture is formed by physical combination, keeps the properties of its components, and can vary in composition.

Question 4Science

A cell from a multicellular organism is observed under a microscope. It has a nucleus, mitochondria, and a cell wall but no chloroplasts. Which type of cell is it most likely to be?

  1. A plant cell from a leaf
  2. A fungal cell Correct answer.
  3. An animal cell from muscle tissue
  4. A bacterial cell

Explanation

Fungal cells are eukaryotic, so they have a nucleus and mitochondria, and they also have a cell wall but no chloroplasts. Bacterial cells lack a nucleus, leaf cells contain chloroplasts, and animal cells lack a cell wall.

Question 5Science

In humans, the allele for free earlobes (F) is dominant to the allele for attached earlobes (f). Two parents who are both heterozygous (Ff) have a child. What is the probability that the child has attached earlobes?

  1. 0 percent
  2. 50 percent
  3. 75 percent
  4. 25 percent Correct answer.

Explanation

A cross of Ff x Ff produces offspring in a 1 FF : 2 Ff : 1 ff ratio. Only the ff genotype shows the recessive attached-earlobe trait, so the probability is 1 in 4, or 25 percent.

Question 6Science

Two populations of the same bird species live on opposite sides of a wide river. Over many generations, the two populations can no longer interbreed successfully. What best explains this outcome?

  1. The two populations were exposed to identical environments and merged.
  2. The birds deliberately decided to become separate species.
  3. Members of the two populations learned different songs and chose not to sing.
  4. Geographic separation prevented gene flow, allowing each population to accumulate different traits. Correct answer.

Explanation

When a physical barrier such as a river prevents gene flow, each isolated population can change independently through mutation, natural selection, and genetic drift. Over many generations these differences can become so great that the populations can no longer interbreed, which is reproductive isolation.

Question 7Science

Which statement best describes the role of natural selection in a population of insects exposed to an insecticide?

  1. All insects in the population become resistant at the same time.
  2. Resistance appears only because insects choose to avoid the chemical.
  3. The insecticide causes individual insects to develop resistance during their lifetimes.
  4. Insects that already carry resistant traits survive and pass those traits to offspring. Correct answer.

Explanation

Natural selection acts on variation that already exists in a population. Insects with inherited traits that help them survive the insecticide reproduce more often, so those traits become more common in later generations.

Question 8Science

A food web in a forest includes grasses, rabbits, foxes, and hawks. If a disease sharply reduces the rabbit population, which change is most likely to occur first?

  1. The fox population will decrease because its food supply is smaller. Correct answer.
  2. The grass population will decrease because fewer rabbits eat it.
  3. The fox population will increase because there is less competition.
  4. The hawk population will immediately become producers.

Explanation

Foxes prey on rabbits, so a sharp drop in the rabbit population reduces the food available to foxes. With less food, fewer foxes can be supported, so the fox population is likely to decline.

Question 9Science

Which process in the water cycle returns water vapor from plants directly into the atmosphere?

  1. Condensation
  2. Precipitation
  3. Transpiration Correct answer.
  4. Runoff

Explanation

Transpiration is the release of water vapor from plant leaves through small openings called stomata. Condensation forms clouds, precipitation returns water to the surface, and runoff moves water across the land.

Question 10Science

A student observes that a certain rock layer contains fish fossils, while the layer directly above it contains bird fossils. What can the student reasonably conclude?

  1. The fish layer is older than the bird layer. Correct answer.
  2. The rock layers formed at exactly the same time.
  3. The birds lived before the fish.
  4. The fish lived after the birds.

Explanation

In undisturbed sedimentary rock sequences, lower layers are generally older than the layers above them. Because the fish layer lies below the bird layer, the fish fossils are older than the bird fossils.

Question 11Science

A student builds a model of Earth's interior. Which statement correctly describes the layer where convection currents move molten rock?

  1. The outer core is solid rock that does not move.
  2. The inner core is liquid and flows like a river.
  3. The crust is the thickest layer and drives plate motion.
  4. The mantle contains slowly flowing material that moves heat and helps drive plate motion. Correct answer.

Explanation

The mantle makes up most of Earth's volume and contains hot rock that flows very slowly over long periods. Convection currents in the mantle transfer heat and help drive the movement of tectonic plates.

Question 12Science

Two tectonic plates slide horizontally past each other along a fault. What type of plate boundary is this, and what event is most likely to occur there?

  1. A transform boundary, where earthquakes are common Correct answer.
  2. A subduction zone, where one plate sinks beneath another
  3. A convergent boundary, where volcanoes always form
  4. A divergent boundary, where new crust is created

Explanation

At a transform boundary, plates move past one another horizontally, and the crust is neither created nor destroyed. The friction and sudden release of built-up stress along the fault produce earthquakes.

Question 13Science

A weather map shows a cold air mass pushing into a warm air mass. Which weather change is most likely as the front passes?

  1. A drop in temperature with heavy precipitation and then clearing Correct answer.
  2. Steady, mild weather with no clouds for many days
  3. A rise in temperature with clear skies
  4. A long period of light drizzle followed by fog

Explanation

At a cold front, dense cold air pushes under warm air, forcing the warm air to rise quickly. This rapid lifting produces tall clouds, heavy precipitation, and often thunderstorms, followed by cooler, drier air.

Question 14Science

Which statement best explains why the Moon shows phases as seen from Earth?

  1. We see different amounts of the Moon's sunlit half as the Moon orbits Earth. Correct answer.
  2. Earth's shadow falls on different parts of the Moon each night.
  3. The Moon changes shape as it moves farther from Earth.
  4. The Moon produces its own light that changes in brightness.

Explanation

The Moon does not emit its own light; it reflects sunlight, and half of it is always lit. As the Moon orbits Earth, we see varying portions of that sunlit half, which produces the phases.

Question 15Science

A student uses a spring scale to pull a box across a rough floor at a constant speed. The scale reads 12 N. What is the magnitude of the friction force acting on the box?

  1. 12 N Correct answer.
  2. 6 N
  3. 24 N
  4. 0 N

Explanation

Constant speed means the net force on the box is zero, so the forward pull must be balanced by an equal and opposite friction force. Since the applied force is 12 N, the friction force is also 12 N.

Question 16Science

A student claims that heavier objects always fall faster than lighter objects. Which observation best challenges this claim when air resistance is small?

  1. Objects fall only when pushed downward.
  2. A heavy ball lands first because it has more mass.
  3. A heavy ball and a light ball dropped together from the same height land at nearly the same time. Correct answer.
  4. A light ball floats upward when released.

Explanation

In the absence of significant air resistance, all objects near Earth's surface accelerate downward at the same rate due to gravity, about 9.8 m/s². A heavy and a light ball released together therefore land at nearly the same time, contradicting the claim.

Question 17Science

A car travels 150 meters in 10 seconds. What is its average speed?

  1. 1500 m/s
  2. 15 m/s Correct answer.
  3. 1.5 m/s
  4. 150 m/s

Explanation

Average speed equals distance divided by time. Dividing 150 meters by 10 seconds gives 15 m/s, which is the car's average speed over the trip.

Question 18Science

A student builds a series circuit with two identical bulbs and a battery. One bulb is removed. What happens to the other bulb?

  1. It becomes brighter than before.
  2. It stays lit at the same brightness.
  3. It goes out because the circuit path is broken. Correct answer.
  4. It flickers but continues to shine.

Explanation

In a series circuit, there is only one path for current to flow. Removing one bulb breaks that path, so current cannot flow and the remaining bulb goes out.

Question 19Science

A bar magnet is placed near a pile of iron nails and paper clips. Which statement best explains why the nails are attracted to the magnet?

  1. The magnetic force acts only on objects that are already magnetized.
  2. The magnet repels the nails, which pushes them away.
  3. The magnetic field of the magnet induces a temporary alignment of magnetic domains in the iron. Correct answer.
  4. The nails have a magnetic field that is stronger than the magnet's field.

Explanation

Iron is a ferromagnetic material, so the magnet's field can align its magnetic domains temporarily and attract it. This induced magnetism explains why unmagnetized iron objects cling to a magnet.

Question 20Science

A wave has a frequency of 5 Hz and a wavelength of 2 meters. What is its speed?

  1. 2.5 m/s
  2. 20 m/s
  3. 10 m/s Correct answer.
  4. 7 m/s

Explanation

Wave speed equals frequency multiplied by wavelength. Multiplying 5 Hz by 2 meters gives 10 m/s.

Question 21Science

A student shines white light through a prism and observes a rainbow band. Which statement best explains this result?

  1. Different colors of light bend by different amounts when they enter and leave the glass. Correct answer.
  2. White light contains only one wavelength that splits into many.
  3. The prism creates new colors by adding energy to the light.
  4. The prism absorbs all light and then re-emits it as a single color.

Explanation

White light is a mixture of wavelengths, and each wavelength refracts, or bends, by a slightly different amount in glass. This separation of colors is called dispersion and produces the visible spectrum.

Question 22Science

A student mixes baking soda and vinegar in a sealed bag and observes bubbles and a temperature drop. Which evidence best indicates that a chemical change occurred?

  1. A new gas is produced that was not present before. Correct answer.
  2. The bag feels cooler to the touch.
  3. The vinegar looks clear before mixing.
  4. The baking soda is a white powder.

Explanation

The formation of a new substance, such as a gas with different properties from the reactants, is strong evidence of a chemical change. Color and physical appearance of the starting materials alone do not show that a reaction occurred.

Question 23Science

Which statement correctly describes the law of conservation of mass in a closed system?

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

Explanation

In a closed system, atoms are rearranged during a chemical reaction but none are created or destroyed. Therefore the total mass of the reactants equals the total mass of the products.

Question 24Science

An element has an atomic number of 17 and a mass number of 35. How many neutrons are in one atom of this element?

  1. 17
  2. 52
  3. 35
  4. 18 Correct answer.

Explanation

The atomic number gives the number of protons, which is 17, and the mass number is the sum of protons and neutrons. Subtracting 17 protons from 35 gives 18 neutrons.

Question 25Science

In the periodic table, elements in the same group (column) tend to have similar chemical properties. Which explanation best accounts for this pattern?

  1. They have the same number of valence electrons in their outermost energy level. Correct answer.
  2. They all exist as gases at room temperature.
  3. They all have the same number of electron shells.
  4. They have identical atomic masses and identical numbers of neutrons.

Explanation

Chemical behavior is largely determined by the number of valence electrons. Elements in the same group share the same number of outermost electrons, which is why they tend to react in similar ways.

Question 26Science

A student compares a plant cell and an animal cell under a microscope. Which structure is present in the plant cell but absent in the animal cell?

  1. Cell wall Correct answer.
  2. Mitochondrion
  3. Nucleus
  4. Cell membrane

Explanation

Plant cells are surrounded by a rigid cell wall made mainly of cellulose, which gives shape and support. Animal cells lack a cell wall and are bounded only by a flexible cell membrane. Both cell types do contain mitochondria and a nucleus.

Question 27Science

Which organelle is the main site of protein synthesis in a cell?

  1. Ribosome Correct answer.
  2. Vacuole
  3. Lysosome
  4. Golgi apparatus

Explanation

Ribosomes assemble amino acids into proteins by following instructions carried by messenger RNA. They may float free in the cytoplasm or attach to the rough endoplasmic reticulum. The other organelles listed handle packaging, digestion, or storage rather than protein assembly.

Question 28Science

During photosynthesis, a green plant takes in carbon dioxide and water. Which substances are the products of this process?

  1. Glucose and carbon dioxide
  2. Glucose and oxygen Correct answer.
  3. Carbon dioxide and water
  4. Oxygen and water

Explanation

Photosynthesis uses light energy to combine carbon dioxide and water into glucose, releasing oxygen as a byproduct. The glucose stores chemical energy that the plant can use or convert to starch. Carbon dioxide and water are the reactants, not the products.

Question 29Science

A student eats a meal containing starch. Which body process breaks the starch into smaller molecules that can be absorbed?

  1. Mechanical chewing only
  2. Filtration in the kidneys
  3. Chemical digestion by enzymes Correct answer.
  4. Absorption in the large intestine

Explanation

Enzymes such as amylase chemically break starch into simpler sugars that can cross the intestine wall. Chewing increases surface area but does not itself split the molecules. Absorption of nutrients happens mainly in the small intestine, not the large intestine.

Question 30Science

Which statement correctly describes the relationship between a predator and its prey in an ecosystem?

  1. Both organisms gain energy from the Sun directly
  2. The prey gains energy by consuming the predator
  3. The predator and prey compete for the same food source
  4. The predator gains energy by consuming the prey Correct answer.

Explanation

In a predator-prey relationship, energy flows from the prey to the predator when the predator eats it. This transfer moves energy up a food chain. The prey does not consume the predator, and only producers capture sunlight directly.

Question 31Science

A student reads that atoms of the same element can have different mass numbers. What are these atoms called?

  1. Isotopes Correct answer.
  2. Ions
  3. Molecules
  4. Compounds

Explanation

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, giving different mass numbers. Because the proton count is unchanged, they remain the same element. Ions differ by electron count, and molecules and compounds involve bonded atoms.

Question 32Science

Which statement best describes what happens to the particles of a liquid as it freezes into a solid?

  1. The particles stop moving completely
  2. The particles break apart into separate atoms
  3. The particles become fixed in place and vibrate less Correct answer.
  4. The particles gain energy and move farther apart

Explanation

Freezing removes energy from the particles, so they settle into fixed positions and vibrate in place. This ordered arrangement is what gives solids a definite shape. The particles still vibrate; they do not stop moving entirely.

Question 33Science

A flashlight is switched on and its bulb glows. Which sequence correctly traces the energy transformation?

  1. Heat energy to light energy to electrical energy
  2. Chemical energy to electrical energy to light and heat Correct answer.
  3. Light energy to chemical energy to electrical energy
  4. Electrical energy to chemical energy to light

Explanation

The battery stores chemical energy, which is converted to electrical energy that flows through the circuit. The bulb then converts electrical energy into light and heat. The other sequences reverse the actual direction of energy flow.

Question 34Science

A student places a small object on a balance and finds its mass is 45 grams. The object is then placed in a graduated cylinder containing 50 mL of water, and the water level rises to 65 mL. What is the density of the object?

  1. 15 g/mL
  2. 0.75 g/mL
  3. 3 g/mL Correct answer.
  4. 0.33 g/mL

Explanation

The volume of the object equals the water displaced, 65 mL minus 50 mL, which is 15 mL. Density is mass divided by volume, so 45 g divided by 15 mL equals 3 g/mL. Dividing by the wrong quantity produces the other choices.

Question 35Science

A student observes that a balloon rubbed with wool cloth sticks to a wall. Which statement best explains this behavior?

  1. The balloon becomes magnetized by the wool
  2. The balloon's mass increases enough to create gravity
  3. The balloon gains a static charge that attracts the neutral wall Correct answer.
  4. The wall loses all of its electrons to the balloon

Explanation

Rubbing transfers electrons between the wool and the balloon, giving the balloon a net static charge. This charged balloon attracts neutral objects such as the wall through electrostatic force. Magnetism involves magnetic poles rather than transferred charge.

Question 36Science

A student observes that a clear liquid turns cloudy when a second clear liquid is added, and a solid settles at the bottom. Which type of change most likely occurred?

  1. A chemical change releasing only light
  2. A physical change of state
  3. A physical change of shape
  4. A chemical change forming a precipitate Correct answer.

Explanation

The formation of a solid from two liquids is a precipitate, which is evidence of a chemical reaction producing a new substance. Changes of state or shape do not create a new solid from dissolved materials. Light release alone is not what the observation describes.

Question 37Science

A class measures the boiling point of a liquid three times and gets 78.1 °C, 78.3 °C, and 78.2 °C. The accepted value is 78.4 °C. Which statement best evaluates these results?

  1. They are precise but slightly inaccurate Correct answer.
  2. They are neither accurate nor precise
  3. They are both accurate and precise
  4. They are accurate but not precise

Explanation

Precision describes how closely repeated measurements agree, and these values cluster tightly together. Accuracy describes closeness to the accepted value, and all three fall slightly below 78.4 °C. The results are therefore precise but slightly inaccurate.

Question 38Science

A certain gene has two alleles. One allele codes for brown eyes and is dominant; the other codes for blue eyes and is recessive. Two parents who are both heterozygous have a child. What is the probability the child will have blue eyes?

  1. 100%
  2. 25% Correct answer.
  3. 75%
  4. 50%

Explanation

Two heterozygous parents each carry one dominant and one recessive allele. A Punnett square gives offspring genotypes in a 1:2:1 ratio, with only one of four combinations being homozygous recessive. Blue eyes therefore appear with a 25% probability.

Question 39Science

A scientist finds that a certain trait appears more often in males than in females within a family. The gene for the trait is located on the X chromosome. Which statement best explains this pattern?

  1. Males have one X chromosome, so one recessive allele is enough to show the trait Correct answer.
  2. Females cannot inherit genes located on the X chromosome
  3. Males have two X chromosomes and must inherit two recessive alleles
  4. The trait is carried on the Y chromosome, which only males have

Explanation

Males inherit one X and one Y chromosome, so a recessive allele on their single X chromosome is expressed. Females have two X chromosomes and need two recessive alleles to show the trait. This difference explains why X-linked recessive traits appear more often in males.

Question 40Science

A population of beetles lives in a habitat where the background color is dark. Over many generations, dark-colored beetles become more common than light-colored beetles. Which explanation best fits this change?

  1. The beetles choose mates based on the background color
  2. Light beetles deliberately change color to match the background
  3. Dark beetles are stronger and defeat light beetles in combat
  4. Dark beetles are better camouflaged and survive to reproduce more often Correct answer.

Explanation

Better camouflage reduces the chance that dark beetles are seen and eaten by predators. Those beetles survive longer and pass their traits to more offspring, so the dark trait becomes more common. Individual organisms do not intentionally change inherited traits.

Question 41Science

A food chain in a pond consists of algae, small fish that eat the algae, and large fish that eat the small fish. Which statement best describes the role of the algae?

  1. They are consumers that eat small fish
  2. They are decomposers that break down dead material
  3. They are producers that capture energy from sunlight Correct answer.
  4. They are top predators in the pond

Explanation

Algae are photosynthetic organisms that capture light energy and make their own food, making them producers. All other organisms in the chain depend on the energy the algae capture. Consumers and decomposers occupy different roles in the ecosystem.

Question 42Science

A student uses a model to show how carbon moves through an ecosystem. Which process returns carbon from living organisms to the atmosphere?

  1. Transpiration
  2. Cellular respiration Correct answer.
  3. Photosynthesis
  4. Condensation

Explanation

Cellular respiration breaks down glucose and releases carbon dioxide as a waste product, returning carbon to the atmosphere. Photosynthesis removes carbon dioxide from the atmosphere instead. Transpiration and condensation involve water, not carbon.

Question 43Science

A student observes that a sample of rock contains layers that are tilted at a steep angle. Which statement best explains how the layers most likely became tilted?

  1. Forces within Earth deformed the rock after the layers formed Correct answer.
  2. The rock layers were tilted by the daily motion of the Sun
  3. The layers were deposited at a steep angle by wind
  4. The layers formed during a single volcanic eruption

Explanation

Sedimentary layers are originally deposited nearly horizontally, so steep tilting indicates later deformation by tectonic forces. The principle that layers begin horizontal is called original horizontality. Wind deposition and volcanic eruptions do not explain the tilting of existing layers.

Question 44Science

A student compares the hardness of four minerals by scratching them against one another. Mineral W scratches mineral X, mineral X scratches mineral Y, and mineral Y scratches mineral Z. Which mineral is the softest?

  1. Mineral W
  2. Mineral X
  3. Mineral Z Correct answer.
  4. Mineral Y

Explanation

A mineral that can be scratched by another is softer than the one that scratches it. Following the chain, W is harder than X, X is harder than Y, and Y is harder than Z. Therefore Z, which scratches nothing, is the softest.

Question 45Science

A student heats a metal ball and finds it no longer fits through a metal ring that it passed through easily when cold. Which statement best explains this result?

  1. The ball became magnetic and attracted the ring
  2. The ring shrank because it lost particles
  3. The ball gained mass as it absorbed heat
  4. The ball expanded because its particles moved farther apart Correct answer.

Explanation

Heating increases the average motion of particles, causing them to spread slightly farther apart and the object to expand. The ball's increased size prevents it from fitting through the ring. The number of particles and the mass do not increase during heating.

Question 46Science

A block is pushed across a level floor with a constant force, but it does not move. Which statement best describes the forces acting on the block?

  1. The applied force is balanced by static friction of equal size Correct answer.
  2. The normal force is zero because the block is at rest
  3. Gravity no longer acts on the block
  4. The applied force is larger than any friction force

Explanation

When an object remains at rest, the net force on it is zero, so forces must balance. Static friction adjusts to match the applied force up to a limit, preventing motion. Gravity still acts, and the normal force balances the block's weight.

Question 47Science

A student rides a bicycle 300 meters east and then 400 meters north. The trip takes 100 seconds. What is the average speed of the student?

  1. 5 m/s
  2. 3 m/s
  3. 1 m/s
  4. 7 m/s Correct answer.

Explanation

Average speed uses total distance traveled, which is 300 m plus 400 m, or 700 m. Dividing 700 m by 100 s gives 7 m/s. The displacement is 500 m, but that value would be used for average velocity, not speed.

Question 48Science

A student builds a parallel circuit with a battery and two identical bulbs. One bulb burns out and stops conducting. What happens to the other bulb?

  1. It becomes brighter because it receives all the current
  2. It flickers on and off rapidly
  3. It stays lit because it has its own separate path to the battery Correct answer.
  4. It goes out because the circuit is now open

Explanation

In a parallel circuit each branch connects independently to the battery, so current can still flow through the remaining branch. The working bulb stays lit at about the same brightness. A break in one branch does not open the other branches.

Question 49Science

A light ray strikes a mirror at an angle of 35° measured from the normal. What is the angle between the reflected ray and the normal?

  1. 55°
  2. 0°
  3. 35° Correct answer.
  4. 70°

Explanation

The law of reflection states that the angle of incidence equals the angle of reflection, both measured from the normal. A ray striking at 35° from the normal therefore reflects at 35° from the normal. The 55° value is the angle measured from the mirror surface instead.

Question 50Science

A student dissolves 20 grams of salt in 80 grams of water in a sealed container. The total mass of the contents is 100 grams. What is the mass of the salt water solution, and why?

  1. 20 grams, because only the dissolved salt has mass
  2. 80 grams, because the salt disappears into the water
  3. 100 grams, because mass is conserved and no matter escaped Correct answer.
  4. 120 grams, because dissolving adds mass to the system

Explanation

Dissolving is a physical change in which the total mass of the matter stays the same. Since the container is sealed and nothing escapes, the solution has the same 100 grams as the combined starting materials. The salt does not vanish; its particles spread among the water particles.