Chapter 7

Which of the following is not evidence that a chemical change has occurred?

• a change in color

• a change in size

• a distinct smell

• a change in temperature

Identify the correctly balanced chemical equation for the following word

equation: Magnesium metal burns in gaseous oxygen to produce magnesium

oxide.

• Mg + O2 → 2MgO

• 2Mg + O2 → 2MgO

• 2Mg + O → 2MgO

• 2Mg + 2O2 → 2MgO2

Tags

NGSS.HS-PS1-7

What is a mole?

• an equation

• a mass

• a quantity

• a ratio

How many moles of hydrogen gas are needed for the following reaction?

N2 + 3H2 → 2NH3

• 1

• 2

• 3

• 6

A key feature of a single-replacement reaction is that

• a single reactant becomes two or more products.

• both reactants and products include an element and a compound.

• two compounds swap ions, producing two new compounds.

• two or more reactants become a single product.

Which of the following occur(s) in a redox reaction?

• An element loses electrons.

• An element gains electrons.

Which of the following reactions require(s) the presence of oxygen?

• combustion

• oxidation

Which of the following does not happen to the energy given off by a campfire?

• Some energy is absorbed by the environment.

• Some energy is given off as light energy.

• Some energy is given off as thermal energy.

• Some energy is destroyed by combustion.

Tags

NGSS.HS-PS3-4

How does a catalyst increase a reaction rate?

• by increasing the concentration of the reactants

• by increasing the number of collisions

• by lowering the activation energy

• by lowering the surface area

Tags

NGSS.HS-PS1-5

What happens to the forward and reverse reactions when a system reaches its

equilibrium state?

• Both the forward and reverse reactions stop.

• The forward and reverse reactions both continue to occur at the same rate.

• The forward reaction stops and the reverse reaction continues to occur.

• The reverse reaction stops and the forward reaction continues to occur.

Tags

NGSS.HS-PS1-6