Question 1

Which of the following diagrams best represents a molecule that is a compound?

Accepted Answer

Diagram IV

Question 2

Refer to the potential energy curves shown. Which curve (solid or dotted) represents the interaction between two atoms forming a covalent bond, and why?

Accepted Answer

The solid line, because it takes more energy to separate the atoms.

Question 3

In the potential energy diagram with points X, Y, and Z, what must happen for the system to move from Y to Z?

Accepted Answer

Energy must transfer from the surroundings to the system, overcoming the interaction between the atoms.

Question 4

A student calibrates a spectrophotometer using a dye solution instead of water. Which hypothetical absorbance plot would result for the dye sample?

Accepted Answer

Hypothetical Plot B

Question 5

Which experiment provided evidence that electrons are negatively charged, and what was the specific evidence?

Accepted Answer

The cathode ray tube experiment; the beam of particles emitted from the cathode bent toward the positively charged plate.

Question 6

In the gold foil experiment diagram, where will the majority of the alpha particles be detected, and why?

Accepted Answer

Position I; the alpha particles go straight through the atom, because it is mostly empty space.

Question 7

Which statement best describes the forces that exist between helium atoms in the solid state?

Accepted Answer

The partial positive end of one atom’s instantaneous dipole attracts the partial negative end of the neighboring atom’s induced dipole.

Question 8

Which of the following best explains why the boiling point of chlorine (Cl$$_2) is $$higher than that of fluorine (F$$_2$$)?

Accepted Answer

Cl$$_2$$ has a larger electron cloud, resulting in stronger London dispersion forces.

Question 9

Which of the following statements about Dalton’s and Thomson’s atomic models is correct?

Accepted Answer

Dalton’s model described atoms as indivisible spheres, while Thomson’s model included negatively charged electrons embedded in a positive sphere.

Question 10

Which equation correctly represents the electrostatic potential energy between two charges $$q_1$$ and $$q_2$$ separated by a distance $$r$$?

Accepted Answer

$$E_p = k_e \frac{q_1$ q_2$}{r}$$

Question 11

A 250 mm$$^3$$ sphere of lithium (density = 0.534 g/cm$$^3) $$contains how many moles of lithium? (Molar mass of Li = 6.94 g/mol)

Accepted Answer

0.019 moles

Question 12

Which of the following statements about the freezing of chlorine (Cl$$_2) is $$true?

Accepted Answer

When chlorine freezes, London dispersion forces are formed.

Question 13

Which of the following best explains why adding thermal energy causes fluorine to change from a liquid to a gas?

Accepted Answer

Thermal energy is used to overcome the intermolecular forces holding the molecules together in the liquid state.

Question 14

Which of the following best describes the evidence that led Rutherford to propose the nuclear model of the atom?

Accepted Answer

A small fraction of alpha particles were deflected at large angles when passing through gold foil.

Question 15

Which of the following statements about the London dispersion forces (LDFs) between two neon atoms and two argon atoms is correct?

Accepted Answer

The LDF between two neon atoms is weaker than the LDF between two argon atoms because neon has a smaller electron cloud.

Question 16

Which of the following best describes the forces that exist between two subatomic particles with opposite charges as they approach each other?

Accepted Answer

The potential energy decreases as the objects get closer together; this could represent a proton and an electron.

Question 17

Which of the following is a scientific question, and why?

Accepted Answer

Yes; it can be tested and answered through observations and experiments.

Practice Exam 1 – General Chemistry Study Guidance

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