Part II. Multiple choice, continued (3 points each). Name:__________________ Please circle your answer. There is only one correct answer to each question. 14. Which of the following compounds would you expect to be ionic? A) SF6 B) H2O C) H2O2 D) CaO 15. Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N2 (g) + 3H2 (g) à 2NH3 (g) A 9.3-g sample of H2 requires ____________ g of N2 for a complete reaction. A) 43 B) 1.3 x 102 C) 3.9 x 102 D) 4.6 16. What is the frequency of light (s-1) that has a wavelength of 1.23 x 10-6 cm? A) 3.69 B) 2.44 x 1016 C) 4.10 x 10-17 D) 9.62 x 1012 17. Which sketch represents an orbital with the quantum numbers n = 3, l = 1, ml = 0? A) B) C) D) 18. What color of visible light has the longest wavelength? A) blue B) violet C) red D) yellow 19. According to the Heisenberg Uncertainty Principle, it is impossible to know precisely both the position and the __________ of an electron. A) mass B) color C) momentum D) shape 20. The wavelength of a photon that has an energy of 5.25 x 10-19 J is ___________ m. A) 3.79 x 10-7 B) 2.64 x 106 C) 2.38 x 1023 D) 3.79 x 107 21. There are ___________ orbitals in the second shell. A) 2 B) 4 C) 9 D) 18

Okay, I can explain the concepts behind those multiple-choice questions in more depth:

14. Ionic Compounds: Ionic compounds are formed through the transfer of electrons between atoms, typically between a metal and a nonmetal. This transfer creates ions (charged particles) that are attracted to each other due to their opposite charges.

• A) SF6 (Sulfur hexafluoride): This is a covalent compound because it consists of two nonmetals (sulfur and fluorine) sharing electrons.
• B) H2O (Water): This is also a covalent compound. Hydrogen and oxygen share electrons.
• C) H2O2 (Hydrogen peroxide): Another covalent compound where hydrogen and oxygen share electrons.
• D) CaO (Calcium oxide): This is an ionic compound. Calcium (Ca) is a metal, and oxygen (O) is a nonmetal. Calcium transfers electrons to oxygen, forming Ca2+ and O2- ions, which are strongly attracted to each other.

15. Stoichiometry: This question involves stoichiometry, which is the calculation of quantitative relationships of the reactants and products in chemical reactions. The balanced equation is:
N2 (g) + 3H2 (g) \rightarrow 2NH3 (g) This equation tells us that 1 mole of nitrogen gas (N2) reacts with 3 moles of hydrogen gas (H2) to produce 2 moles of ammonia (NH3).

• First, find the number of moles of H_2:
  Moles = \frac{mass}{molar \, mass} = \frac{9.3 \, g}{2.016 \, g/mol} \approx 4.6 \, moles
• According to the balanced equation, 3 moles of H2 react with 1 mole of N2. Therefore, the number of moles of N2 needed is: Moles \, of \, N2 = \frac{Moles \, of \, H_2}{3} = \frac{4.6 \, moles}{3} \approx 1.53 \, moles
• Now, convert moles of N_2 to grams:
  Grams = moles \times molar \, mass = 1.53 \, moles \times 28.02 \, g/mol \approx 43 \, g
• A) 43: correct

16. Frequency of Light: The relationship between the speed of light (c), wavelength (λ), and frequency (ν) is given by the equation:
c = \lambda \nu
Where:

• c = speed of light (3.00 \times 10^{10} cm/s)
• λ = wavelength (1.23 x 10-6 cm)
• ν = frequency (s-1)
  Solve for frequency (ν):
  \nu = \frac{c}{\lambda}
  \nu = \frac{3.00 \times 10^{10} \, cm/s}{1.23 \times 10^{-6} \, cm} \approx 2.44 \times 10^{16} \, s^{-1}
• B) 2.44 \times 10^{16}: This is the correct frequency.

17. Atomic Orbitals: The quantum numbers define the properties of atomic orbitals:

• n (principal quantum number): Describes the energy level of the electron (n = 3 means the third energy level).
• l (azimuthal quantum number): Describes the shape of the orbital (l = 0 is an s orbital, l = 1 is a p orbital, l = 2 is a d orbital).
• ml (magnetic quantum number): Describes the orientation of the orbital in space (ml = 0).
  Given n = 3 and l = 1, we are looking for a p orbital in the third energy level with a specific orientation (ml = 0). P orbitals have a dumbbell shape, and since ml = 0, it should be oriented along one of the axes.
  -The correct sketch (needs to be visualized) should represent a p orbital (dumbbell shape) oriented along one of the axes in a 3D space.

18. Visible Light Spectrum: The visible light spectrum ranges from violet to red. The wavelengths increase in the order:

• Violet
• Blue
• Green
• Yellow
• Orange
• Red
• C) Red: Red light has the longest wavelength in the visible spectrum.

19. Heisenberg Uncertainty Principle: The Heisenberg Uncertainty Principle states that it is impossible to determine with perfect accuracy both the position and momentum (which is mass times velocity) of a particle. The more accurately you know one, the less accurately you can know the other.

• C) momentum: The correct answer is momentum.

20. Energy of a Photon: The energy (E) of a photon is related to its wavelength (λ) by the equation:
E = \frac{hc}{\lambda}
Where:

• E = energy (5.25 \times 10^{-19} J)
• h = Planck’s constant (6.626 \times 10^{-34} J s)
• c = speed of light (3.00 \times 10^{8} m/s)
  Solve for λ:
  \lambda = \frac{hc}{E}
  \lambda = \frac{(6.626 \times 10^{-34} \, J \cdot s)(3.00 \times 10^{8} \, m/s)}{5.25 \times 10^{-19} \, J}
  \lambda \approx 3.79 \times 10^{-7} \, m
• A) 3.79 \times 10^{-7}: The correct wavelength is 3.79 \times 10^{-7} m.

21. Orbitals in the Second Shell:

• The second electron shell (n = 2) has two subshells: l = 0 (s orbital) and l = 1 (p orbital).
• For l = 0 (s orbital), there is one orbital (ml = 0).
• For l = 1 (p orbital), there are three orbitals (ml = -1, 0, +1).
• Total number of orbitals in the second shell = 1 (s) + 3 (p) = 4.
• B) 4: There are 4 orbitals in the second shell.