Which of these is a pure substance?
A bar of gold
Soil
Blood
A drop of melted wax falls on a table. It cools and becomes solid. How has it changed?
It not longer has a fixed volume
Its atoms have stopped moving
It has a fixed shape
Suppose that you examine an unknown liquid. You determine that it contains a single type of molecule. What is the liquid?
A pure substance
A heterogeneous mixture
A homogeneous mixture
An example of evaporation is when:
Ice in a freezer slowly forms ice crystals
Grass wet with dew slowly dries in the morning sunshine
Just-washed hands are rubbed on a towel
Which of these is a physical change, not a chemical change?
Ripening apples turning red
Rusting tools become reddish brown
Painting a cloth red
As your stomach digests food, this would be considered a:
Physical change
Chemical change
Matter state change
Which of the following choices contains only physical properties?
mass, color, ability to rust
ability to be shaped, volume, ability to burn
ability to break, ability to bend, texture
As a solid heats up, its particles gain energy and vibrate faster. When they vibrate enough, the particles move away from one another. This describes
freezing
evaporation
melting
Which of these has the highest melting point?
a stainless steel teaspoon
ice
cooking oil
A red liquid and a yellow liquid are mixed together. The result is an orange liquid that bubbles. This is evidence of
physical change
chemical change
physical property
A red and yellow liquid are mixed together. The result is an orange liquid. This is evidence of a
Which of these is a chemical change, not a physical change?
A sweater turns purple from a grape juice stain
Burning wood turns into ashes and smoke
Bubbles escape from boiling water
During the phase change lab, the H2O molecules were
moving faster and spreading out
slowing down and getting closer
becoming more dense
