Q: A photon is emitted during an electron transition in a hydrogen atom from $$n=4 to$$ $$n=2. $$Which equation correctly calculates the energy of the emitted photon?

$$E = h \nu = \frac{hc}{\lambda}$$

Q: Given the wavelength $$\lambda = 486 \text{ nm}$$ for a photon emitted by hydrogen, what is the frequency $$\nu of $$the photon? (Use $$c = 3.00 \times 10^8$ \text{ m/s})$$

$$\nu = \frac{c}{\lambda} = \frac{3.00 \times 10^8$}{486 \times 10$$^{-9}$$} \approx 6.17 \times 10$$^{14}$$ \text{ Hz}$$

Q: Given the following bond energies: $$\text{N-H} = 391 \text{ kJ/mol}$$, $$\text{O-H} = 463 \text{ kJ/mol}$$, calculate the enthalpy change for the reaction: $$\text{NH}_3 + \text{H}_2O \rightarrow \text{NH}_2 + \text{H}_3O^+. $$Assume one N-H bond is broken and one O-H bond is formed.

$$\Delta H = 391 - 463 = -72 \text{ kJ/mol}$$

Q: Which equation correctly represents the dissociation of H$$_2SO$_4 in $$water?

$$\text{H}_2\text{SO}_4 (aq) \rightarrow 2\text{H}^+ (aq) + \text{SO}_4$$^{2-}$$ (aq)$$

Q: What is the molarity of a solution prepared by dissolving 5.00 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 250.0 mL of solution?

$$M = \frac{5.00}{58.44} \div 0.250 = 0.342 \text{ M}$$

Question 1

A photon is emitted during an electron transition in a hydrogen atom from $$n=4 to$$ $$n=2. $$Which equation correctly calculates the energy of the emitted photon?

Accepted Answer

$$E = h 
u = \frac{hc}{\lambda}$$

Question 2

Which of the following best describes the difference between absorption and emission spectra?

Accepted Answer

Absorption spectra show dark lines where light is absorbed, while emission spectra show bright lines where light is emitted.

Question 3

Given the wavelength $$\lambda = 486 	ext{ nm}$$ for a photon emitted by hydrogen, what is the frequency $$
u of $$the photon? (Use $$c = 3.00 	imes 10^8$ 	ext{ m/s})$$

Accepted Answer

$$
u = \frac{c}{\lambda} = \frac{3.00 	imes 10^8$}{486 	imes 10$$^{-9}$$} \approx 6.17 	imes 10$$^{14}$$ 	ext{ Hz}$$

Question 4

Which quantum number determines the shape of an orbital?

Accepted Answer

Angular momentum quantum number $$l$$

Question 5

Which rule states that electrons fill degenerate orbitals singly before pairing up?

Accepted Answer

Hund's Rule

Question 6

Which of the following electron configurations is NOT allowed by the Pauli Exclusion Principle?

Accepted Answer

Two electrons in the same orbital with the same spin

Question 7

Which orbital diagram correctly represents the ground state of oxygen ($$Z=8$$)?

Accepted Answer

1s$$^2 2s$^2 2p$^4$$ with two paired and two unpaired electrons in 2p

Question 8

Which of the following molecules violates the octet rule?

Accepted Answer

BF$$_3$$

Question 9

What is the formal charge on the central atom in the nitrate ion, NO$$_3^-$$, in its most stable resonance structure?

Accepted Answer

0

Question 10

Given the following bond energies: $$	ext{N-H} = 391 	ext{ kJ/mol}$$, $$	ext{O-H} = 463 	ext{ kJ/mol}$$, calculate the enthalpy change for the reaction: $$	ext{NH}_3 + 	ext{H}_2O ightarrow 	ext{NH}_2 + 	ext{H}_3O^+. $$Assume one N-H bond is broken and one O-H bond is formed.

Accepted Answer

$$\Delta H = 391 - 463 = -72 	ext{ kJ/mol}$$

Question 11

Which statement about bond length and bond energy is correct?

Accepted Answer

Shorter bonds have higher bond energies.

Question 12

What is the molecular geometry of SF$$_6$$ according to VSEPR theory?

Accepted Answer

Octahedral

Question 13

Which bond angle is expected in a molecule with tetrahedral geometry?

Accepted Answer

$$109.5^\circ$$

Question 14

Which of the following molecules is polar?

Accepted Answer

NH$$_3$$

Question 15

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

CH$$_2O$$

Question 16

Which of the following is a strong electrolyte?

Accepted Answer

NaCl (aq)

Question 17

Which equation correctly represents the dissociation of H$$_2SO$_4 in $$water?

Accepted Answer

$$	ext{H}_2	ext{SO}_4 (aq) ightarrow 2	ext{H}^+ (aq) + 	ext{SO}_4$$^{2-}$$ (aq)$$

Question 18

What is the molarity of a solution prepared by dissolving 5.00 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 250.0 mL of solution?

Accepted Answer

$$M = \frac{5.00}{58.44} \div 0.250 = 0.342 	ext{ M}$$

Question 19

If 100.0 mL of a 1.00 M HCl solution is diluted to a final volume of 500.0 mL, what is the final concentration?

Accepted Answer

$$M_1$$ $$V_1$$ = $$M_2$$ $$V_2$$ \Rightarrow $$M_2$$ = \frac{1.00 	imes 100.0}{500.0} = 0.200 	ext{ M}$$

General Chemistry Study Guide: Atomic Structure, Bonding, and Solutions

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