8th Grade Eog Review Test

Which is a compound?

• Sodium

• Sugar

• Nitrogen

• Air

Which is the best estimate of the melting point of Rubidium (Rb)?

• 25°C

• 40°C

• 75°C

• 184°C

Two different liquids are poured together in an open container. Bubbles begin to form. After the bubbling stops, it is determined that the total weight of the two liquids is less than before they were poured together. Which best describes this observation?

• Some of the atoms during the reaction escaped into the air.

• Some of the atoms during the reaction were destroyed.

• Some of the atoms during the reaction became heavier.

• Some of the atoms during the reaction changed to a different kind of atom.

This is a chemical reaction for the decomposition of carbonic acid into water and carbon dioxide.

H2CO3 → H2O + CO2

How does the reaction support the Law of Conservation of Mass?

• Several molecules of water are produced.

• The mass of carbon atoms is reduced during the reaction.

• The mass of the atoms in the reactant equals the mass of the atoms in the products.

• The mass of hydrogen atoms is the only thing that remains the same before and after the reaction.

Which best describes a method of obtaining energy that may cause changes in water temperature and harm to fish populations?

• burning coal

• using ethanol in cars

• installing solar panels on a home

• generating electricity in a hydroelectric power plant

Which is a nonrenewable resource?

• Oil

• Sunlight

• Water

• Wood

How would a large increase in the salinity of an estuary most likely affect the ecosystem of the estuary?

• All organisms would die.

• All organisms would continue to live as they now do.

• The number of salt-tolerant organisms would increase, and the number of salt-intolerant organisms would decrease.

• The number of salt-intolerant organisms would increase, and the number of salt-tolerant organisms would decrease.

Which would indicate the water in a lake is not safe for drinking?

• many varieties of fish in the lake

• high dissolved-oxygen levels in the lake

• cold water temperature of the lake

• high turbidity levels in the lake

A geologist identifies the identical index fossils in rock layers from two different areas. Which conclusion is best supported by this discovery?

• The deposition rate of the two rock layers was identical.

• The fossil organism evolved independently in the two separate areas.

• The two rock layers were deposited at approximately the same time.

• The index fossil will also occur in sediment deposited on top of these rock layers.

Which supports the theory that some mountains were once at the bottom of an ocean?

• There are underwater mountains on the ocean floor today.

• Freshwater rivers flow to the ocean.

• Fossils of marine organisms are found on the tops of some mountains.

• Both mountains and ocean floors have similar minerals in their rocks.