Which reaction below represents the electron affinity of Se?
A) Se(g) → Se*(g) +e
B) Se”(g) → Se(g) + e
C) Se(g) +e” → Se (g)
D) Se2-(8) ► Se (g)+ e N will have the lowest freezing point.
3) of the following, a 0.1 M aqueous solution of
A) potassium chromate
B) sodium chloride f) sodium sulfate Daluminum nitrate E) pure water 4) Each of the following sets of quantum numbers is supposed to specify an orbital. Choose the one set of quantur numbers that DOES NOT contain an error. AD n = 4,1 = 0, m/=-1 B) n = 5,1 = 3, m/=-3 C) n = 3,7 = 2, m/=+3 D) n = 4,1 = 4, m =0 E) n = 3,7 = 1, m = -2 5) Which molecule or compound below contains a polar covalent bond? A) C₂H4 B) AgCI C) Lil D) Zns )Nci3 6) Which of the following represents the core electron configuration (by filling) for lodine?
The Correct Answer and Explanation is :
Let’s go through each of the questions and provide the correct answers with explanations:
1) Which reaction below represents the electron affinity of Se?
The electron affinity is the energy change when an electron is added to a neutral atom in the gas phase. For selenium (Se), the correct reaction would be:
C) Se(g) + e⁻ → Se⁻(g)
Explanation: The electron affinity refers to the process where a neutral atom (Se in this case) gains an electron to form a negatively charged ion (Se⁻). This process releases energy.
2) Which of the following has the lowest freezing point?
The solution with the lowest freezing point will be the one that has the greatest amount of dissolved particles (since freezing point depression is proportional to the number of solute particles in the solution).
Answer: D) Aluminum nitrate (Al(NO₃)₃)
Explanation: When aluminum nitrate dissolves in water, it dissociates into Al³⁺ and 3 NO₃⁻ ions, resulting in 4 total ions. Potassium chromate (K₂CrO₄) dissociates into 3 ions, sodium chloride (NaCl) into 2 ions, and sodium sulfate (Na₂SO₄) into 3 ions. Therefore, Al(NO₃)₃ produces the most ions and would cause the greatest freezing point depression.
3) Which set of quantum numbers does NOT contain an error?
Quantum numbers define the properties of electrons in atoms, and there are certain rules for allowable values. The set that does not contain an error is:
Answer: B) n = 5, l = 3, mₗ = -3
Explanation: The principal quantum number (n) can be any positive integer, the azimuthal quantum number (l) can be any integer from 0 to (n-1), and the magnetic quantum number (mₗ) can range from (-l) to (+l). In this case, for (n = 5), (l = 3) is allowed, and (mₗ = -3) is a valid value.
The other sets contain errors:
- A) (l = 0) is fine, but (mₗ = -1) is not valid for (l = 0) (it should be 0).
- C) (l = 7) is not valid for (n = 3) (it must be between 0 and (n-1), which would be 0 to 2).
- D) (l = 4) is invalid for (n = 4) (it should be between 0 and 3).
- E) (mₗ = -2) is invalid for (l = 1) (it should be between -1 and 1).
4) Which molecule or compound below contains a polar covalent bond?
A polar covalent bond occurs when electrons are shared unequally between atoms due to differences in electronegativity.
Answer: E) NCl₃
Explanation: Nitrogen (N) and chlorine (Cl) have different electronegativities, so the bond between them is polar. The other compounds do not have polar covalent bonds:
- A) C₂H₄ (ethene) has nonpolar covalent bonds because the electronegativity difference between C and H is very small.
- B) AgCl is an ionic compound, not a covalent bond.
- C) LiI is also ionic due to the large electronegativity difference between lithium (Li) and iodine (I).
- D) ZnS is ionic.
5) Core electron configuration of iodine (I)
Answer: The core electron configuration for iodine is:
[Kr] 4d¹⁰ 5s² 5p⁵
Explanation: Iodine has an atomic number of 53. The electron configuration starts with the nearest noble gas, Krypton (Kr), which has the configuration [Kr] 4d¹⁰ 5s² 5p⁵. These are the core electrons, meaning the electrons in the inner energy levels, excluding the valence electrons (the ones in the outermost shell). The valence configuration for iodine is 5s² 5p⁵, with the last electron being added to the p orbital.
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