Question 1

A student investigates the Law of Conservation of Mass by observing the chemical equation for photosynthesis:

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

. Based on the Law of Conservation of Mass and the provided equation, which statement best describes the atoms in this reaction?

Accepted Answer

The total number of atoms for each element is the same in the reactants and the products because atoms are only rearranged.

Answer

The number of oxygen atoms increases because the plant produces gas as a byproduct.

Answer

Some carbon atoms are destroyed during the reaction to release energy for the plant's growth.

Answer

The total mass of the products is greater than the reactants because a new sugar molecule was created.

Question 2

A student is given a sample of an unknown element. The sample is shiny, solid at room temperature, and can be hammered into thin sheets without breaking. Based on these physical properties, in which section of the Periodic Table is this element most likely located?

Accepted Answer

Metals

Answer

Nonmetals

Answer

Metalloids

Answer

Noble Gases

Question 3

A student was given the chemical formula for glucose,

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

. According to TEKS 7.6(B), how many total atoms of Oxygen (O) are present in three molecules of glucose?

Accepted Answer

18

Answer

6

Answer

12

Answer

24

Question 4

A student observes a small insect walking across the surface of a pond without sinking. Which property of water, resulting from the attraction between water molecules at the surface, allows this to happen?

Accepted Answer

Surface tension

Answer

Chemical reactivity

Answer

Density

Answer

Adhesion

Question 5

A student is testing two different liquids in a lab. Liquid A has a pH of 3, and Liquid B has a pH of 10. Based on these pH values, how should the student classify these substances compared to pure water?

Accepted Answer

Liquid A is an acid, and Liquid B is a base.

Answer

Liquid A is neutral, and Liquid B is a strong acid.

Answer

Both liquids are acidic because they are not a neutral pH of 7.

Answer

Liquid A is a base, and Liquid B is an acid.

Question 6

A student is given a test tube containing a mixture of sand and salt water. After the sand settles to the bottom, the student observes that the salt is completely dissolved in the water and appears uniform throughout the liquid portion. According to TEKS 8.6(A), how should the student classify the salt water and the sand-water combination?

Accepted Answer

The salt water is a homogeneous mixture, and the sand-water combination is a heterogeneous mixture.

Answer

The salt water is a heterogeneous mixture, and the sand-water combination is a homogeneous mixture.

Answer

Both the salt water and the sand-water combination are classified as pure substances.

Answer

The salt water is a compound, and the sand-water combination is an element.

Question 7

A student conducts an experiment where they place a solid block with a density of

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

into a beaker containing four different liquids. In which of the following liquids would the block float?

Accepted Answer

Liquid X with a density of

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

Answer

Liquid Y with a density of

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

Answer

Liquid W with a density of

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

Answer

Liquid Z with a density of

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

Question 8

A student monitors a reaction in a closed system where a piece of magnesium ribbon is burned. The student observes a bright flash of light and the formation of a white powdery substance, magnesium oxide (

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

). Which evidence best supports the classification of this process as a chemical change according to TEKS 7.6(C)?

Accepted Answer

The formation of a new substance with different properties and the release of energy in the form of light.

Answer

The fact that the mass of the magnesium doubled because a new substance was created out of nothing.

Answer

The magnesium ribbon dissolving into the air and disappearing completely.

Answer

The change in the shape of the magnesium as it was handled before the reaction.

Question 9

A student performs an experiment in a sealed flask where a solution of silver nitrate reacts with a solution of sodium chloride to form a solid precipitate and a new liquid solution. If the initial mass of the flask and the reactants is

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

, what will be the total mass after the reaction is complete?

Accepted Answer

Exactly

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

because mass is conserved in a closed system.

Answer

Variable, depending on how many atoms were destroyed during the chemical change.

Answer

Slightly more than

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

because the precipitate adds weight to the flask.

Answer

Slightly less than

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

because a solid was formed from liquids.

Question 10

A student views the following chemical equation in a science journal:

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

. Which statement correctly uses the Periodic Table to identify the atoms involved in this reaction according to TEKS 8.6(B)?

Accepted Answer

The reaction involves 4 total atoms of Hydrogen and 2 total atoms of Oxygen.

Answer

The reaction involves 4 total atoms of Water and 2 total atoms of Helium.

Answer

The reaction involves 2 total atoms of Hydrogen and 1 total atom of Oxygen.

Answer

The reaction involves 2 total atoms of Helium and 2 total atoms of Oxygen.

Question 11

A student is investigating the Law of Conservation of Mass using the chemical equation for photosynthesis:

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

. Which of the following best explains why this equation supports the law in a closed system?

Accepted Answer

The total number of atoms for each element is the same in both the reactants and the products.

Answer

The state of matter of the products has more mass than the state of matter of the reactants.

Answer

Energy is produced during the reaction which adds to the total mass of the sugar molecule.

Answer

The number of molecules on the reactant side is equal to the number of molecules on the product side.

Question 12

A scientist is identifying an unknown substance in the lab. The substance has a pH of 3, turns blue litmus paper red, and reacts with certain metals to produce hydrogen gas. Based on TEKS 8.6(D), how should this substance be classified compared to pure water?

Accepted Answer

As an acid, because its pH is lower than the neutral pH of 7.

Answer

As a metal, because it responds to the physical properties of rare Earth elements.

Answer

As a base, because its pH is higher than the neutral pH of 7.

Answer

As a neutral liquid, because its pH is equal to that of pure water.

Question 13

A student is examining a sample of matter. The sample consists of two different types of atoms that are chemically bonded together in a fixed ratio, forming a pure substance. According to TEKS 8.6(A), how should this sample be classified?

Accepted Answer

Compound

Answer

Element

Answer

Heterogeneous mixture

Answer

Homogeneous mixture

Question 14

A student observes a water strider walking across the surface of a pond without sinking. According to TEKS 8.6(C), which property of water is most responsible for supporting the insect's weight on the surface?

Accepted Answer

Surface tension caused by cohesion

Answer

The pH level of the pond water

Answer

The density of the water relative to the insect

Answer

Adhesion to the insect's legs

Question 15

A student is given a sample of a solid element that is shiny, easily conducts electricity, and can be hammered into thin sheets without breaking. Based on TEKS 6.6(C), in which section of the Periodic Table is this element most likely located?

Accepted Answer

Metals

Answer

Nonmetals

Answer

Metalloids

Answer

Noble Gases

Question 16

A student observes a chemical formula for magnesium hydroxide:

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

. According to TEKS 7.6(B), what is the total number of atoms represented in one molecule of this substance?

Accepted Answer

5

Answer

4

Answer

6

Answer

3

Question 17

A student places four different solid cubes into a large container of liquid. Based on the concept of density relative to fluids (TEKS 6.6D), which of the following observations most likely indicates that a cube has a density greater than the liquid?

Accepted Answer

The cube sinks to the bottom of the container.

Answer

The cube floats on the surface of the liquid.

Answer

The cube dissolves and forms a homogeneous mixture.

Answer

The cube remains suspended in the exact middle of the fluid.

Question 18

A student performs an experiment by mixing baking soda and vinegar in a sealed Ziploc bag. During the reaction, bubbles form and the bag expands, but the mass of the bag remains the same as it was before the reaction. According to TEKS 8.6(E) and 7.6(C), which statement best describes this occurrence?

Accepted Answer

A chemical change occurred where atoms were rearranged to form a gas, but mass was conserved in the closed system.

Answer

A physical change occurred because the state of matter changed while the atoms remained in their original molecules.

Answer

A chemical change occurred because new atoms were created by the energy of the reaction.

Answer

A physical change occurred because the total number of molecules increased to fill the bag.

Question 19

A student is using the Periodic Table to analyze a chemical reaction between sodium (Na) and chlorine (Cl). According to TEKS 8.6(B) and 7.6(B), how many total atoms of reactants are represented in the balanced equation

6CO_{2} + 6H_{2}O \rightarrow C_{6}H_{12}O_{6} + 6O_{2}

?

Accepted Answer

4

Answer

5

Answer

2

Answer

3

Question 20

A student is observing how water travels from the roots of a plant to its leaves. This process is possible because water sticks to the walls of the plant's xylem tubes. According to TEKS 8.6(C), which property of water is best demonstrated by this 'sticking' to the tube walls?

Accepted Answer

Adhesion

Answer

Surface tension

Answer

Density

Answer

Cohesion

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