1
Which of the following is the simplest form of a substance?
A. Element
B. Compound
C. Mixture
D. Chemical
Element
A student is attempting to explain the differences between elements and compounds. Which of the following statements are true for elements?
Select two correct answers.
A. Elements are pure substances.
B. Elements are composed of two or more elements.
C. H2O is an example of an element.
D. Elements are represented by a chemical symbol.
E. Elements are represented by chemical formulas.
A. Elements are pure substances.
D. Elements are represented by a chemical symbol.
Which of the following properties of a substance could change during a physical change?
A. ability to rust
B. reactivity with acids
C. resistance to bending
D. ability to burn in oxygen
C. resistance to bending
How can you increase the concentration of a saturated solution to become a supersaturated solution? Select two correct answers.
A. stir the solution
B. heat the solution
C. add more solvent
D. cool the solution
E. increase the size of the container
A. stir the solution
B. heat the solution
To speed up the dissolving process of a solute, a student can ___________ the surface area of the particle and ___________ the temperature of the solvent.
increase
Which of the following examples most closely represents what it means to be an element?
A gum ball machine with many different colors and sizes of candy inside.
B. A fish tank holding a large variety of fish.
C. A salad made of lettuce, tomatoes, cucumbers, and dressing.
D. A brick wall made from many identical bricks.
D. A brick wall made from many identical bricks.
Table sugar, C12H22O11 is a chemical compound used in many cake recipes. How many different elements make up this chemical compound?
A. 2
B. 3
C. 5
D. 6
B. 3
Which of the following is an example of a new substance being formed by a chemical change?
A. milk souring
B. water evaporating
C. iron bending
D. helium-filled balloon floating
A. milk souring
In an aqueous solution, what is always used as the solvent?
A. oil
B. alcohol
C. water
D. liquid soap
C. water
How does stirring a solution affect the rate of dissolution?
A. It increases the solubility of the solute particles in the solvent.
B. It increases the interaction between solute and solvent particles.
C. It decreases the temperature of the solvent.
D. It decreases the surface area of the solute.
B. It increases the interaction between solute and solvent particles.
Which of the following chemical formulas are examples of a chemical compound created when two or more elements chemically combine to create a new substance?
Select TWO correct answers.
A. aluminum
B. sodium bromide
C. water
D. mercury
E. lead
B. sodium bromide
C. water
Acetic acid is a compound found in vinegar. The chemical formula for acetic acid is CH3COOH.
How many different elements are in acetic acid?
A. 3
B. 5
C. 6
D. 8
A. 3
Mrs. Johnston heated 5 grams of sugar. The sugar first looked shiny, then melted and became dark brown. Finally, all that was left was a black, shiny substance. She then heated 5 grams of sand in the same way. The sand’s appearance did not change. What explains these results?
A. Sand is an element, but sugar is a compound.
B. Heating the sugar caused a chemical change.
C. Heating the sand caused a chemical change.
D. Heating the sugar caused it to melt.
B. Heating the sugar caused a chemical change.
What are two things that an aqueous solution needs?
A. salt
B. oil
C. solute
D. sugar
E. solvent
C. solute
E. solvent
What happens when you stir a solution that contains a solid solute?
A. The solubility decreases.
B. The solute dissolves more quickly.
C. The solute dissolves more slowly.
D. The solvent evaporates faster.
B. The solute dissolves more quickly.
Which of the following is an element?
A. Al
B. NaCl
C. CO
D. H2O
Al
Cu + 2AgNO3 → 2Ag + Cu(NO3)2
How many copper (Cu) atoms are there in Cu(NO3)2 ?
A. 1
B. 2
C. 5
D. 6
A. 1
Which of the following are examples of chemical changes?
Select TWO correct answers.
A. rust forming on a car door
B. water evaporating out of a cup
C. burning a log
D. dissolving sugar into water
E. Cutting a piece of paper
A. rust forming on a car door
C. burning a log
A student pours salt into a glass of water and stirs the water. The salt crystals seem to disappear because they are —
A. melting
B. evaporating
C. boiling
D. dissolve
D. dissolve
Which of the following actions will slow down the rate of dissolution of a solid solute in water?
A. increasing the temperature
B. stirring the solution
C. decreasing the surface area of the solute
D. increasing the surface area of the solute
C. decreasing the surface area of the solute
Which of the following substances would be identified as a compound?
Select TWO correct answers.
A. H2
B. O
C. CO
D. NaBr
E. N2
C. CO
D. NaBr
Which of the following are physical changes?
Select TWO correct answers.
A. iron rusting
B. copper changing color
C. boiling water
D. hydrogen and oxygen producing water
E. ice cream melting
C. boiling water
E. ice cream melting
In a sugar-water solution, sugar is the_______ and water is the __________.
sugar is the solute and water is the solvent
A student places one teaspoon of sugar in a small beaker of water. What will happen to the sugar?
A. It will change into water.
B. It will dissolve in the water.
C. It will melt to form a liquid.
D. It will keep all its properties.
B. It will dissolve in the water.
How can the rate of dissolution be increased? Choose 2 answers.
A. Decrease the temperature of the solution.
B. Increase the temperature of the solution.
C. Increase the size of the solute in the solution.
D.Stir or agitate the solution while adding the solute.
E. Decrease the container of the solution.
B. Increase the temperature of the solution.
D. Stir or agitate the solution while adding the solute.