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#1. What term names molten rock expelled by a volcano?
Lava is molten rock expelled onto Earth’s surface; magma remains underground.
#2. What force causes unsupported objects to fall toward Earth?
Gravity attracts mass toward Earth’s center, so unsupported objects fall.
#3. Which scientific law states that matter is neither created nor destroyed in a chemical reaction?
In a closed chemical system, total mass remains constant.
#4. What is the most abundant gas in Earth’s atmosphere by volume?
Nitrogen makes up about 78 percent of dry air by volume.
#5. In the water cycle, which process changes liquid water into water vapor?
Evaporation turns liquid water into water vapor.
#6. Which rule correctly describes the force between two magnetic poles?
Opposite magnetic poles attract; like poles repel.
#7. Which two of these are noble gases?
Select all that apply:
Argon and neon sit in group 18; nitrogen and chlorine do not.
#8. Sound travels faster through water than through air.
Sound moves at roughly 1,480 m/s in water versus about 343 m/s in air.
#9. What is the chemical symbol for iron?
Iron’s symbol Fe comes from the Latin ferrum.
#10. Order these states of water from lowest to highest energy.
Energy rises from solid through liquid and gas to ionised plasma.