FREE GACE Chemistry Test Questions and Answers

Question 1

Which substance has the greatest chance of being a solid at STP?

Accepted Answer

Na

Answer

At Standard Temperature and Pressure (STP), which is 0°C (273.15 K) and 1 atm (101.325 kPa), sodium (Na) is a solid metal. Krypton (Kr) and Xenon (Xe) are noble gases, and ammonia (NH3) is a gas at STP. Therefore, sodium is the substance most likely to be a solid under these conditions.

Question 2

Which of the following actions might raise a solution's freezing point?
I. Divide the mixture between two different containers. 
II. To boil off some of the solvent, heat the solution.
III. Start a reaction that will result in some of the solute precipitating.

Accepted Answer

III

Answer

The freezing point of a solution is affected by the concentration of the solute. Removing solute from a solution, such as by precipitation (III), effectively lowers the solute concentration. A lower solute concentration means the solution is closer to being pure solvent, which would raise its freezing point towards that of the pure solvent. Boiling off solvent (II) would increase solute concentration, lowering the freezing point, and dividing the mixture (I) doesn't change the concentration.

Question 3

Cooling occurs to a gas with constant volume. Which gas-related claim must be accurate?

Accepted Answer

The gas molecules' kinetic energy has decreased.

Answer

Temperature is a direct measure of the average kinetic energy of the molecules within a substance. When a gas is cooled, its temperature decreases, which means the average kinetic energy of its constituent molecules also decreases. This reduction in molecular motion is the fundamental reason for the drop in temperature.

Question 4

At STP, two moles of hydrogen and one mole of oxygen gas are mixed together in a closed container. Which of the ensuing assertions is accurate?

Accepted Answer

Greater than partial pressure of oxygen is partial pressure of hydrogen.

Answer

According to Dalton's Law of Partial Pressures, the partial pressure of a gas in a mixture is proportional to its mole fraction. Since there are two moles of hydrogen and one mole of oxygen, hydrogen has a greater mole fraction (2/3 vs 1/3). Therefore, the partial pressure of hydrogen will be greater than the partial pressure of oxygen.

Question 5

What link between two different materials can be best determined using Graham's law?

Accepted Answer

Mass and Diffusion Rate

Answer

Graham's Law of Diffusion states that the rate of diffusion or effusion of a gas is inversely proportional to the square root of its molar mass. This law is specifically used to compare the diffusion rates of two different gases based on their masses. Therefore, it best determines the link between mass and diffusion rate for different materials (gases).

GACE - Georgia Assessments for the Certification of Educators Practice Test

GACE - Georgia Assessments for the Certification of Educators Practice Test

FREE GACE Chemistry Test Questions and Answers