Which statement is correct for a collision between reactant particles leading to a reaction?

• All reactant particles must have the same energy

• Colliding particles must have the same velocity

• Colliding particles must have kinetic energy higher than the activation energy

• Colliding particles must have different energy

Two clear liquids are mixed in a test tube which results in a yellow solid forming in the clear liquid.  What is the evidence that a chemical reaction took place?

• The fact that the liquid remains clear

• The fact you mixed two different liquids

• The fact that a precipitate formed

• The fact that the temperature didn’t change

What does the limiting reactant do to a reaction?

• It decreases the speed of the reaction.

• It increases the speed of the reaction.

• It starts the reaction once it is added.

• It stops the reaction once it runs out.

What is the type of reaction for the chemical equationC₂H₅OH + O₂ → CO₂ + H₂O

• Synthesis

• Single Replacement

• Combustion

• Decomposition

Covalent bonds are formed between two or more nonmetals, while ionic bonds are formed between a nonmetal and a metal. Which TWO pairs of elements will form covalent bonds between the atoms?

• sulfur and fluorine

• carbon and oxygen

• sodium and bromine

• potassium and chlorine

• lithium and phosphorus

Which statement explains why the elements produce different colors in the flame test?

• The elements are exposed to different heat levels during the flame test, causing a release of different amounts of energy.

• The elements are exposed to different types of gases during the flame test, causing a release of different amounts of energy.

• The movement of electrons between energy orbitals for each element is unique, producing unique wavelengths of light.

• The number of protons remaining after the flame has interacted with the atom is unique, producing unique wavelengths of light.

Which model correctly shows the bonded and unbonded electrons in the covalent bond for ammonia, NH₃?

• 
• 
• 
• 

Which picture correctly models magnesium bromide?

• 
• 
• 
• 

The student creates the atomic nucleus shown.

How many electrons should he add to the model to show a neutrally-charged atom?

• 7

• 10

• 14

• 18

Which element is shown in the student's model?

• neon

• nickel

• fluorine

• potassium