8th Grade Science EOG Diagnostic Assessment

• X is an element, Y is a compound, Z is a mixture.

• X is a compound, Y is a mixture, Z is an element.

• X is a mixture, Y is an element, Z is a compound.

• X is an element, Y is a mixture, Z is a compound.

• Protons and neutrons are in the nucleus and are similar in size; electrons orbit outside the nucleus and are much smaller.

• Electrons and neutrons are in the nucleus; protons orbit outside.

• Protons orbit the nucleus; neutrons and electrons are inside the nucleus together.

• All three particles have approximately the same mass and are scattered throughout the atom.

• Potassium will be chemically unreactive, like the noble gases.

• Potassium will react in a similar way to sodium because they are in the same group.

• Potassium will be a nonmetal because it has more protons than sodium.

• Potassium will behave exactly like chlorine because they are in the same period.

• An ice cube melts into liquid water in a glass.

• Sugar dissolves completely in a cup of warm tea.

• A piece of bread is toasted, turning brown and giving off a burnt smell.

• A glass window is broken into small pieces.

• A gas (bubbles) forms without the liquid being heated.

• Two clear liquids are mixed and a solid (precipitate) forms.

• A substance changes color and cannot be changed back easily.

• Water is poured from a tall glass into a wider bowl.

• A candle burns and releases heat and light.

Select all that apply.

• Less than 50.0 g, because burning destroys some matter.

• Exactly 50.0 g, because mass is conserved in a closed system.

• More than 50.0 g, because oxygen from outside the jar joins the steel wool.

• Exactly zero, because all of the steel wool has burned away.

• The equation has unequal hydrogens and oxygens on each side; balancing shows that atoms are conserved during a chemical reaction.

• The equation is already balanced; atoms are destroyed, and the equation shows how.

• The equation needs to be balanced so the total number of molecules is the same on each side.

• Balancing simply makes the equation look neater; it has no connection to a physical law.

• It began as an epidemic in a single region and then became a pandemic when it spread across multiple continents.

• It is an endemic disease because it is present at all times in one community.

• It is a pandemic only — no epidemic stage ever occurred.

• It cannot be classified because it spread too quickly.

• The frog population will increase because the remaining pond is smaller and easier to navigate.

• The frog population will remain exactly the same because frogs can adapt instantly.

• The frog population will likely decrease because a key abiotic factor (water) has been reduced, limiting shelter and breeding space.

• The frog population will immediately evolve gills to live on land.

• Decomposers produce their own food from sunlight and do not interact with other organisms.

• Decomposers break down dead organisms and waste from every trophic level, returning nutrients to the ecosystem.

• Decomposers are eaten by the heron at the top of the web.

• Decomposers only break down producers, not consumers.

• The student is right — plants do not need food in any sense, because sunlight is all they need.

• Plants make their own food (sugars) using sunlight, water, and carbon dioxide; they use this food for energy and as building material for growth.

• Plants get their food only from the soil, not from sunlight.

• Plants do not grow — they only absorb energy.

• About 10,000 units, because energy is conserved and passes completely up the food chain.

• About 1,000 units.

• About 10 units.

• Zero units, because energy does not transfer between trophic levels.

• Carbon leaves the food web entirely when organisms die.

• Carbon moves from producers to consumers to decomposers, and is returned to the atmosphere and soil to be reused by producers.

• Carbon only flows one way, from decomposers up to producers.

• Carbon is created new by producers during photosynthesis.

• The three species have a recent common ancestor; the modification of the same basic limb structure in each species is explained by natural selection acting over long periods.

• The three species evolved completely independently; the similarity is coincidence.

• The three species are the same species; differences in shape are individual variation only.

• The similarity shows that natural selection plays no role in evolution.

• The fossils in Layer B are older than the fossils in Layer D.

• The fossils in Layer B are younger than the fossils in Layer D.

• The fossils in both layers are exactly the same age.

• The ages cannot be compared without carbon dating.

• The rock layers in all three places formed at about the same time and can be correlated using the trilobite as an index fossil.

• Trilobites are still alive today in all three locations.

• The rock layers in different places must contain the same minerals.

• Fossils cannot be used as evidence of Earth's history.

• Igneous rock, because the intense heat preserves organic remains.

• Sedimentary rock, because organisms are buried and preserved as layers of sediment build up over time.

• Metamorphic rock, because heat and pressure preserve fossils perfectly.

• Fossils are found equally often in all three rock types.

• The majority of Earth's water is salt water in the oceans; most of the remaining fresh water is locked in ice caps and glaciers, and only a tiny fraction is in accessible surface and groundwater.

• Most of Earth's water is fresh water in lakes and rivers.

• Groundwater makes up more than half of all water on Earth.

• All of Earth's water is in the oceans.

• A large underground reservoir where water is stored beneath the rock.

• The land area that drains all of its water into a common river, lake, or ocean outlet.

• A deep ocean current that carries cold water toward the equator.

• A mixture of fresh and salt water where a river meets the sea.

• The amount of sunlight reaching the ocean and the phases of the moon.

• Temperature and salinity — cold, salty water is denser and sinks, while warmer, less-salty water rises.

• The rotation of the Earth and volcanic activity on the sea floor.

• Ocean pollution and shipping traffic.

• The currents raise temperatures in coastal regions where warm water arrives, moderating their climate.

• The currents have no measurable effect on the climate of coastal regions.

• The currents cool coastal regions by blocking sunlight from reaching them.

• The currents only affect marine life; they do not transport heat.

• Site 1; dissolved oxygen is too high.

• Site 3; dissolved oxygen (3.4 mg/L) is below the healthy threshold of 6 mg/L, which means aquatic animals may suffocate.

• Site 4; pH is too acidic for aquatic life.

• Site 2; temperature alone is high enough to kill all aquatic life.

• Fertilizers used on farmland contain nitrogen. Runoff can carry nitrates into nearby waterways, raising nitrate levels downstream.

• Nitrates form naturally only in warm water, so Site 3 has the highest nitrates because of its temperature.

• High turbidity prevents nitrates from forming, so Site 3 should have the lowest nitrates (the data must be wrong).

• Nitrates are harmless and do not come from human activity.

• The health of a water supply depends on many physical, chemical, and biological factors. Protecting it well requires ongoing monitoring, treatment, enforceable standards, and community stewardship working together.

• Only water treatment plants matter; monitoring and stewardship are unnecessary.

• Water quality is not a human responsibility, so no strategy is needed.

• Natural processes always restore water quality without any human action.

• Solar (sunlight).

• Coal.

• Wind.

• Natural gas.

• Geothermal.

• Hydroelectric.

• Petroleum (oil).

Select all that apply.

• Global temperatures have decreased steadily since 1880.

• The sharp rise in global temperature since roughly 1970 coincides with the period of rapid industrialization and fossil fuel use.

• Temperatures and industrial activity are unrelated.

• The graph shows that temperatures are only affected by volcanic activity.

• Fossil fuels are unlimited, so there is no reason to change.

• Renewable sources are naturally replenished and produce far fewer greenhouse gases; combining renewable energy with conservation reduces long-term environmental harm and dependence on finite resources.

• Renewable energy cannot provide any useful power, so conservation is pointless.

• Conservation harms the environment by reducing economic growth.