Category 1: Conservation of Mass
When a log burns in a campfire, the total mass of the system:
A) Increases
B) Decreases
C) Stays the same
D) Doubles
C) Stays the same
Which of the following is a physical change?
A) Rusting of iron
B) Melting of ice
C) Burning paper
D) Cooking an egg
B) Melting of ice
Which state of matter has a definite shape and definite volume?
A) Solid
B) Liquid
C) Gas
D) Plasma
A) Solid
Density is calculated using the formula:
A) Mass ÷ Volume
B) Volume ÷ Mass
C) Mass × Volume
D) Mass – Volume
A) Mass ÷ Volume
What are the units for density?
The Law of Conservation of Mass states:
A) Mass can be created but not destroyed
B) Mass can be destroyed but not created
C) Mass is created and destroyed during chemical reactions
D) Mass is neither created nor destroyed in chemical reactions
D) Mass is neither created nor destroyed in chemical reactions
When sugar dissolves in water, this is considered:
A) Chemical change because bonds break
B) Physical change because it can be reversed by evaporation
C) Chemical change because new substances are made
D) Physical change because it releases heat
B) Physical change because it can be reversed by evaporation
As temperature increases, the particles of a substance generally:
A) Slow down
B) Stay the same speed
C) Speed up
D) Stop moving
C) Speed up
If an object has a mass of 20 g and a volume of 10 mL, its density is:
A) 0.5 g/mL
B) 2 g/mL
C) 10 g/mL
D) 200 g/mL
B) 2 g/mL
Which of the following is an independent variable (IV) in an experiment testing how sunlight affects plant growth?
A) Height of the plants
B) Amount of sunlight each plant receives
C) Type of soil used
D) Amount of water each plant receives
B) Amount of sunlight each plant receives
If 20 g of hydrogen reacts with 80 g of oxygen to form water, what is the total mass of water produced?
A) 20 g
B) 60 g
C) 80 g
D) 100 g
D) 100 g
Which of the following is the BEST evidence of a chemical change?
A) Change in shape
B) Change in size
C) Production of gas
D) Phase change
C) Production of gas
(New substance!)
On a heating curve, what happens to temperature during a phase change (like melting)?
A) It increases steadily
B) It decreases steadily
C) It stays constant
D) It fluctuates randomly
C) It stays constant
An object will float in water if its density is:
A) Greater than 1 g/mL
B) Less than 1 g/mL
C) Equal to 1 g/mL
D) Greater than its mass
B) Less than 1 g/mL
Which statement correctly describes an endothermic process?
A) Heat is released into the surroundings (feels warm)
B) Heat is absorbed from the surroundings (feels cold)
C) Energy is destroyed during the reaction
D) No energy transfer occurs
B) Heat is absorbed from the surroundings (feels cold)
During a reaction, the reactants have a measured mass of 150 g. If the products are a total of 145 g, what most likely happened?
A) Some products escaped as gas
B) New mass was created
C) The scale malfunctioned
D) Mass was destroyed
A) Some products escaped as gas
A student leaves milk out on the counter and it sours. This is an example of:
A) Physical change because it smells different
B) Chemical change because bacteria created new substances
C) Physical change because it can be frozen
D) Chemical change because the milk got warm
B) Chemical change because bacteria created new substances
In a heating curve graph of water, the flat line between 100°C and 100°C represents:
A) Melting
B) Freezing
C) Boiling/Condensation
D) Sublimation
C) Boiling/Condensation
A rock has a mass of 60 g and a volume of 30 cm³. Will it float in water?
A) Yes, because its density is less than water
B) No, because its density is greater than water
C) Yes, because mass is less than 100 g
D) No, because rocks always sink
B) No, because its density is greater than water
Elements in the same column (group) on the periodic table have:
A) The same number of protons
B) The same mass number
C) The same properties because they have the same number of valence electrons
D) The same color and density
C) The same properties because they have the same number of valence electrons
Explain why mass sometimes seems to “disappear” in reactions like burning wood, and how this still follows the Law of Conservation of Mass.
The mass escapes the system as gas. (seems like it is destroyed but it is just lost to the environment- it still exists)
Describe how you could tell the difference between melting butter and frying an egg in terms of physical vs. chemical changes.
Melting is physical, a phase change the butter is still butter. Frying the egg is a chemical change there would be a color change, temperature change and cannot be undone (new bonds formed).
Draw or describe how a heating curve looks for water from solid ice to gas, and explain why the temperature stays the same during phase changes.
A heating curve for water shows temperature increasing as energy is added, but stays constant during melting and boiling, appearing as horizontal plateau- It would be a flat line (on the graph) during the phase change.
A block of wood has a density of 0.8 g/mL. Explain why it floats on water.
It will float because its density is less than the density of water, which is 1 g/mL.
A student is testing how temperature affects the time it takes for sugar to dissolve in water. Identify the independent variable, dependent variable, and one constant.
IV: Temperature of water
DV: Time it takes for sugar to dissolve
Constants: Amount of water, amount of sugar, type of sugar