Unit 4 Assessment: Chem. Equations, Nuclear Chemistry, Solutions

Which of the following variables has the least effect on the rate a substance dissolves in a container of water?

•  the force of the stirring

•  the size of the container

• the temperature of the water

• the surface area (size) of the solute

NaCl is an unsaturated solution when you add 30 grams of solute to water at 40°C. 

How would you create a saturated solution of NaCl without changing the temperature?

•   Increase the amount of water in the solution.

• Add approximately 9 grams of NaCl to the solution.

• Add approximately 12 grams of NaCl to the solution.

• Increase the surface area of NaCl

The four points on the diagram represent four solutions of the unknown salt.

Which point represents a supersaturated solution of the unknown salt?

• Q

• R

• S

• T

The diagram shows a reaction.

Which statement correctly describes this type of reaction and the overall energy change that occurs?

•  The reaction is fission, and energy is absorbed.

• The reaction is fusion, and energy is released

• The reaction is fusion, and energy is absorbed.

•  The reaction is fission, and energy is released.

What type of energy production involves the splitting of nuclei in large, heavy atoms?

• nuclear fusion

•  nuclear fission

• biomass reaction

• chemical reaction

Radioactive isotopes

•  have very unstable nuclei.

• have the most stable nuclei.

• have more electrons than protons.

• have emitted all of their neutrons.

The graph shows the radioactive decay rate of iodine-131.

Based on the graph, what is the half-life of iodine-131?

• 24 days

• 16 days

• 8 days

• 4 days

The dissolved substance in a solution is the

• solute

• solvent

• tincture

• suspension

What is another term for weak solutions?

• concentrated solutions

• dilute solutions

• saturated solutions

• supersaturated solutions

This graph shows the amount of various solutes that will dissolve in 100 grams of water at specific temperatures.

According to the data described by this graph, which chemical would be less soluble at 50C than at 20C?

• NaCl

• KCl

•  KNO₃

• . Ce₂(SO₄)₃