Physical Science Semester 2 Final Exam

Which condition must be met in order for an equation to be balanced?

• The elements in the reactants are the same as the elements in the products.

• There are fewer elements in the reactants than there are in the products.

• The number of atoms in the reactants is greater than the number of atoms in the products.

• The number of atoms in the reactants equals the number of atoms in the products.

Which balances the equation Mg + O₂ → MgO?

• Mg + 2O₂ → 4MgO

• 2Mg + 2O₂ → 2MgO

• 2Mg + O₂ → 2MgO

• 2Mg + 2O₂ → 4MgO

Lexi is balancing equations. She is finding one equation to be very difficult to balance. Which explains how to balance the equation ZnSO₄ + Li₂CO₃ → ZnCO₃ + Li₂SO₄?

• One reactant and one product needs the coefficient 2.

• The products both need a 3 coefficient.

• The reactants both need a 2 coefficient.

• Atoms in the equation are already in balance.

Hydrochloric acid and sodium hydroxide can be combined to form sodium chloride and water. Which best explains the reaction?

• The mass of sodium hydroxide will result in the same mass of sodium chloride.

• The total mass of hydrochloric acid and sodium hydroxide will result in a lower total mass of sodium chloride and water.

• The mass of hydrochloric acid will result in the same mass of sodium chloride.

• The total mass of hydrochloric acid and sodium hydroxide will result in the same total mass of sodium chloride and water.

Which best describes a chemical reaction?

• the rearrangement of atoms by breaking and reforming chemical bonds

• a reaction that absorbs heat from the surroundings

• a reaction that releases heat to the surroundings

• the rearrangement of molecules based on temperature and pressure

The Statue of Liberty is made out of copper and was once shiny and copper-colored. Over the years, the copper has gone through a process called oxidation, where it has changed into a new material. What has occurred?

• an endothermic reaction

• an energy formation

• a chemical reaction

• a precipitate formation

Harvey mixes two liquids. Which observation of the new mixture most likely indicates a precipitate is forming?

• a cloudy appearance

• a bubble formation

• a change in color

• a change in odor

Chemical A and Chemical B react in an exothermic reaction. What can be known about what will happen when Chemical A and Chemical B are mixed together?

• The old substance will need more energy to break its chemical bonds than the new substance will release.

• More energy will be released from the old substance than the new substance will release to form its chemical bonds.

• The color will change as a result of the reaction.

Who is known as the "father of modern chemistry” because he first organized all known elements into four different groups?

• Johann Wolfgang Döbereiner

• Antoine Lavoisier

• Dmitri Mendeleev

• Henry Moseley

The elements in group 17 of the periodic table are all called halogens. All halogens have the same

• atomic number

• atomic mass

• number of possible isotopes

• number of valence electrons