3RD QUARTERLY TEST REVIEW SCIENCE 8

A glass of water is placed in a freezer overnight. How does the arrangement and motion of the water molecules change when it turns into ice?

• Molecules move faster and spread apart

• Molecules slow down and become more organized

• Molecules remain in the same arrangement but move slower

• Molecules disappear and reform when thawed

When sugar dissolves in water, it seems to disappear. What happens to the sugar molecules?

• They break apart into atoms and form a new substance

• They spread out evenly among the water molecules

• They stop moving and settle at the bottom

• They are destroyed by water molecules

A metal rod is heated over a flame. What happens to the motion of its atoms?

• Atoms slow down and move closer together

• Atoms stop moving

• Atoms vibrate more and spread slightly apart

• The metal rod disappears

Water evaporates from a puddle on a sunny day. How does this affect the movement of water molecules?

• They move slower and come together

• They gain energy, move faster, and spread into the air

• They turn into smaller molecules

• They stop moving completely

A student notices that a balloon shrinks when placed in a refrigerator. What happens to the gas particles inside the balloon?

• They slow down and move closer together

• They disappear and leave an empty space

• They increase in energy and spread apart

• They stop moving

A solid piece of dry ice turns into gas without melting into a liquid. What type of physical change is this?

• Condensation

• Freezing

• Sublimation

• Deposition

An atom has an atomic number of 15 and a mass number of 31. How many neutrons does it have?

• 15

• 16

• 31

• 46

An atom of chlorine has 17 protons. How many electrons does it have in a neutral state?

• 8

• 17

• 34

• 18

Which subatomic particle determines the identity of an element?

• Proton

• Neutron

• Electron

• Nucleus

A certain atom has 12 protons, 12 neutrons, and 12 electrons. What is its mass number?

• 12

• 24

• 36

• 48