U.S. Virgin Islands NGSS Science Summative Assessment — Grade 8

A student measures a block of aluminum with a mass of 54 grams and a volume of 20 cubic centimeters. What is the density of the aluminum block?

• A0.37 g/cm³
• B2.7 g/cm³
• C7.4 g/cm³
• D1080 g/cm³

What happens to the arrangement and motion of water molecules when liquid water boils and turns into steam?

• AMolecules move closer together and slow down
• BMolecules separate further apart and move much faster
• CMolecules break apart into individual hydrogen and oxygen atoms
• DMolecules stop moving completely

When 12 grams of carbon react completely with 32 grams of oxygen gas in a closed container, what is the total mass of carbon dioxide produced?

• A20 grams
• B32 grams
• C44 grams
• D56 grams

Synthetic polymers such as plastics are made by chemically altering natural resources. Which of the following natural resources is the primary raw material used to produce most synthetic plastics?

• APetroleum (crude oil)
• BLimestone
• CIron ore
• DSolar energy

A sea turtle swims a distance of 180 meters in 60 seconds. What is the average speed of the sea turtle?

• A0.3 m/s
• B3.0 m/s
• C120 m/s
• D10,800 m/s

A book sitting on a smooth classroom desk remains at rest. Which statement best explains why the book does not move?

• ANo gravitational force is acting on the book
• BThe forces acting on the book are balanced
• CFriction is the only force acting on the book
• DThe book has zero mass

A toy car with a mass of 2 kg accelerates at 4 m/s² across the floor. What net force was applied to the toy car?

• A0.5 N
• B2.0 N
• C6.0 N
• D8.0 N

Which of the following changes will result in the greatest increase in an object's kinetic energy?

• ADoubling its mass while keeping speed constant
• BDoubling its speed while keeping mass constant
• CHalving its speed while doubling mass
• DReducing both mass and speed by half

A metal spoon is placed into a mug of hot cocoa. After a few minutes, the handle of the spoon feels warm. By which heat transfer process did thermal energy travel through the metal spoon?

• AConduction
• BConvection
• CRadiation
• DEvaporation

A light wave travels through space. What property of the wave determines its brightness or intensity?

• AWavelength
• BFrequency
• CAmplitude
• DWave speed

Which statement best describes the structural difference between pure elemental oxygen gas (O2) and a molecule of carbon dioxide (CO2)?

• AO2 contains only one type of element, while CO2 is a compound containing two different el…
• BO2 is a compound, while CO2 is a mixture of gases
• CO2 molecules are larger than CO2 molecules because oxygen is heavier than carbon
• DCO2 contains ionic bonds, while O2 contains no chemical bonds

During an experiment, a student mixes baking soda and vinegar in a beaker. The temperature of the mixture drops from 22°C to 15°C. What type of reaction occurred, and what happened to thermal energy?

• AExothermic reaction; thermal energy was released into the surroundings
• BEndothermic reaction; thermal energy was absorbed from the surroundings
• CExothermic reaction; mass was created during the reaction
• DEndothermic reaction; mass was destroyed during the reaction

In a balanced chemical equation for the formation of water (2H2 + O2 -> 2H2O), how many total hydrogen atoms and oxygen atoms are present on the reactant side compared to the product side?

• A4 hydrogen and 2 oxygen on both sides
• B2 hydrogen and 2 oxygen on the reactant side; 4 hydrogen and 1 oxygen on the product side
• C4 hydrogen and 1 oxygen on both sides
• D2 hydrogen and 1 oxygen on both sides

Two students push a crate across a floor. Student A pushes with a force of 35 N to the right, while Student B pushes with a force of 15 N to the left. What is the net force acting on the crate?

• A50 N to the right
• B20 N to the right
• C20 N to the left
• D50 N to the left

Two bar magnets are held near each other on a table. When the north pole of Magnet 1 is brought close to the north pole of Magnet 2, what will happen to the magnetic force between them as the distance between them decreases?

• AThe attractive force increases
• BThe repulsive force increases
• CThe repulsive force decreases
• DThe magnetic force becomes zero

How does the gravitational force between two planets change if the mass of one planet is doubled while the distance between them remains constant?

• AThe gravitational force stays the same
• BThe gravitational force decreases by half
• CThe gravitational force doubles
• DThe gravitational force quadruples

A 4 kg boulder sits at the top of a 10-meter-high cliff. Taking acceleration due to gravity as 9.8 m/s², what is the gravitational potential energy of the boulder relative to the ground?

• A39.2 J
• B40 J
• C392 J
• D784 J

A 1,000 kg roller coaster cart travels at a speed of 10 m/s. What is its kinetic energy?

• A5,000 J
• B10,000 J
• C50,000 J
• D100,000 J

Container A holds 100 mL of water at 80°C, and Container B holds 500 mL of water at 80°C. Which container has more thermal energy, and why?

• AContainer A, because smaller volumes retain thermal energy faster
• BContainer B, because it contains more total water particles at the same average kinetic e…
• CBoth containers have equal thermal energy because their temperatures are identical
• DContainer A, because its particles move faster than those in Container B

An ocean wave has a wavelength of 4 meters and a frequency of 0.5 Hz (waves per second). What is the speed of the ocean wave?

• A0.125 m/s
• B2.0 m/s
• C4.5 m/s
• D8.0 m/s

When a light ray travels from air into a glass prism, it bends. What causes this light bending (refraction)?

• ALight speeds up when entering denser glass
• BLight changes speed as it passes from one medium into another
• CLight absorbs energy and shifts its frequency
• DLight reflects off the outer surface of the glass at 90 degrees

Why are digital signals (such as binary code) generally more reliable than analog signals for transmitting information over long distances?

• ADigital signals travel at the speed of sound rather than the speed of light
• BDigital signals can be recreated without noise or distortion because they consist of dist…
• CDigital signals do not require any electromagnetic waves to transmit data
• DAnalog signals lose frequency while digital signals increase in wavelength

Synthetic fertilizers have greatly increased crop yields worldwide. However, agricultural runoff containing these fertilizers often enters nearby coastal waters. What major environmental problem is caused by this runoff?

• AOzone layer depletion
• BAlgal blooms that deplete dissolved oxygen and harm aquatic life
• CIncreased groundwater acidity that stops seed germination
• DReduction in atmospheric carbon dioxide levels

A student rubs a rubber balloon against her wool sweater, giving the balloon a negative static charge. When she brings the balloon near small pieces of paper, the paper is pulled toward the balloon. Why does this occur?

• AGravitational force between the balloon and paper increases
• BElectric fields exert forces on electric charges without direct physical contact
• CMagnetic poles on the paper align with the sweater
• DAir pressure around the balloon decreases significantly

A student tests four different materials (aluminum foil, foam board, glass, wool cloth) to determine which makes the best thermal insulator for a warm water container. Which property identifies the best thermal insulator?

• AThe material that allows heat to flow through it fastest
• BThe material that causes the greatest temperature drop of the warm water over 20 minutes
• CThe material that minimizes heat transfer, resulting in the smallest water temperature dr…
• DThe material with the highest electrical conductivity

A sample of nitrogen gas in a rigid metal container is heated from 20°C to 80°C. What happens to the gas particles inside the container?

• AThey expand in size and slow down
• BTheir average kinetic energy increases, causing them to collide more frequently and force…
• CThey condense into liquid nitrogen droplets on the container bottom
• DTheir mass increases as thermal energy converts into matter

Which of the following observations provides definitive evidence that a chemical reaction has occurred rather than just a physical change?

• AA liquid freezes into a solid at 0°C
• BA sugar cube dissolves completely in warm water
• CA solid precipitate forms when two clear liquids are mixed
• DA large copper sheet is cut into four smaller pieces

A 60 kg swimmer pushes off the wall of a pool with a force of 120 N to the left. According to Newton's third law of motion, what force does the pool wall exert on the swimmer, and what is the swimmer's initial acceleration?

• A120 N to the right; acceleration of 2.0 m/s²
• B120 N to the left; acceleration of 0.5 m/s²
• C60 N to the right; acceleration of 1.0 m/s²
• D0 N; the pool wall does not move so it exerts no force

A 0.5 kg ball is dropped from rest from a height of 20 meters. Assuming no air resistance and taking g = 9.8 m/s², what is the kinetic energy of the ball just before it strikes the ground?

• A9.8 J
• B49 J
• C98 J
• D196 J

An irregularly shaped metal object with a mass of 150 grams is submerged in a graduated cylinder containing 50 mL of water. The water level rises to 70 mL. What is the density of the metal, and will it float or sink in pure water (density = 1.0 g/mL)?

• A2.14 g/mL; float
• B7.5 g/mL; sink
• C3.0 g/mL; sink
• D0.13 g/mL; float

Gamma rays have a much higher frequency than radio waves. How do their wavelengths and speeds in a vacuum compare?

• AGamma rays have longer wavelengths and travel faster than radio waves
• BGamma rays have shorter wavelengths and travel at the exact same speed as radio waves
• CGamma rays have shorter wavelengths and travel slower than radio waves
• DGamma rays have longer wavelengths and travel at the same speed as radio waves

The acceleration due to gravity on the Moon is approximately 1.6 m/s², compared to 9.8 m/s² on Earth. An astronaut has a mass of 70 kg. What are the astronaut's mass and weight on the Moon?

• AMass = 70 kg; Weight = 112 N
• BMass = 11.4 kg; Weight = 112 N
• CMass = 70 kg; Weight = 686 N
• DMass = 43.7 kg; Weight = 70 N

Equal masses (100 g) of water (specific heat = 4.18 J/g°C) and iron (specific heat = 0.45 J/g°C) at 20°C absorb the same amount of thermal energy (1,000 J). Which substance will reach a higher final temperature, and why?

• AWater, because its higher specific heat allows it to absorb heat without expanding
• BIron, because its lower specific heat means less energy is required to raise its temperat…
• CBoth will reach the exact same temperature because their masses and energy inputs are equ…
• DWater, because liquid molecules move faster than solid iron atoms

A student burns 5.0 grams of magnesium ribbon in an open crucible to produce magnesium oxide (MgO). After the reaction, the mass of the white ash in the crucible is 8.3 grams. Does this violate the law of conservation of mass?

• AYes, because mass was created out of energy during combustion
• BNo, because oxygen gas from the surrounding air reacted with the magnesium, adding mass t…
• CYes, because chemical reactions always increase total mass
• DNo, because the mass of magnesium decreased while the density increased

Two sound waves travel through the same room. Wave A has an amplitude of 1 unit, and Wave B has an amplitude of 3 units. How does the energy transported by Wave B compare to Wave A?

• AWave B carries 3 times as much energy as Wave A
• BWave B carries 6 times as much energy as Wave A
• CWave B carries 9 times as much energy as Wave A
• DWave B carries the same energy as Wave A because their speeds are identical

Which organelle is present in plant cells but NOT in animal cells, providing structural support and rigidity to the cell?

• ACell membrane
• BCell wall
• CMitochondria
• DNucleus

What are the primary reactants needed by plant cells to carry out photosynthesis?

• AGlucose and oxygen
• BCarbon dioxide and water
• COxygen and water
• DNitrogen and glucose

In a Caribbean coral reef food web, what role do photosynthetic marine algae play?

• APrimary consumers
• BDecomposers
• CProducers
• DApex predators

Where is genetic information (DNA) stored within a eukaryotic cell?

• ARibosome
• BVacuole
• CNucleus
• DCytoplasm

Which of the following is a characteristic feature of asexual reproduction?

• AOffspring inherit genetic material from two parents
• BOffspring are genetically identical to the single parent
• COffspring always have greater genetic diversity
• DOffspring require sperm and egg fertilization

Why do cacti in arid desert environments have thick, waxy stems and needle-like leaves?

• ATo maximize water loss through transpiration
• BTo absorb sunlight during the night
• CTo reduce water loss and protect against herbivores
• DTo attract pollinators with bright green foliage

What does the discovery of fossilized marine sea shells on top of a high mountain range indicate about Earth's history?

• AAncient sea creatures could walk on land
• BThe mountain area was once covered by an ocean before being uplifted
• CSea shells were carried to the mountaintop by ancient birds
• DVolcanic eruptions formed sea shells from lava

Which two body systems work together to deliver oxygen from inhaled air to muscle cells throughout the body?

• ADigestive system and nervous system
• BRespiratory system and circulatory system
• CSkeletal system and endocrine system
• DExcretory system and integumentary system

Which statement correctly describes the energy transformation that occurs during photosynthesis in chloroplasts?

• AChemical energy stored in sugar is converted into light energy
• BLight energy from the Sun is transformed into chemical energy stored in glucose
• CThermal energy is converted into nuclear energy
• DElectrical energy is converted into mechanical energy

How are photosynthesis and cellular respiration complementary processes in Earth's ecosystems?

• APhotosynthesis produces carbon dioxide and water, which cellular respiration uses to prod…
• BPhotosynthesis uses oxygen and glucose to release energy, while cellular respiration abso…
• CThe products of photosynthesis (glucose and oxygen) are the reactants for cellular respir…
• DBoth processes consume carbon dioxide to release oxygen into the atmosphere

In a forest ecosystem, a disease drastically reduces the population of deer. Which of the following is an immediate likely effect on the ecosystem?

• AThe population of plants eaten by deer will decrease
• BThe population of predators (such as wolves) that feed on deer will decrease or face food…
• CDecomposer activity in the forest will stop entirely
• DSunlight reaching the forest floor will decrease

In an ecological energy pyramid, approximately 10% of the energy at one trophic level is transferred to the next level. If producers contain 50,000 kJ of energy, how much energy is available to secondary consumers?

• A50,000 kJ
• B5,000 kJ
• C500 kJ
• D50 kJ