Nomenclature & Stoichiometry
Periodic Trends & Bonding
Lewis Structures & VSEPR
Hybridization & Bond Types
Molecular Orbital Theory
100

Question #9

  1. Convert grams → moles

    moles=18.33/100.09

  2. Multiply by Avogadro’s number

    molecules=moles×6.022×10^23

Answer: D (1.10 × 10²³ molecules)

100

Question #11

  • Larger electronegativity difference = more ionic

Order:
Si–P < Si–S < Si–Cl

Answer: B

100

Question #12

S (6) + 4O (24) + 2 extra = 32

Answer: C

100

Question #21

  • 6 electron groups → octahedral
  • 2 lone pairs → square planar

Answer: A

100

Question #26

  • 2 AOs → 2 MOs (one lower (bonding), one higher energy (antibonding))

Answer: C

200

Question #10

  1. Assume 100 g → convert % → grams
  2. Convert grams → moles
  3. Divide by smallest mole
  4. Multiply to get whole numbers

Result:
C ≈ 5, H ≈ 7, N ≈ 1

Answer: D (C₅H₇N)

200

Questions #18 and #19

  • Triple bond = shortest & strongest

HC≡CH wins both

Answers:

  • 18 → C
  • 19 → C 
200

Question #13

  • Tetrahedral → 109.5°

Answer: C

200

Question #22

  • Steric number = 4 → sp³

Answer: B

200

Question #27

  • Highest bond order = most stable

C₂²⁻ wins

Answer: E

300

Question #1

An empirical formula = simplest whole-number ratio of atoms.

Check each!

Answer: B (already simplified)

300

Question #20

Boron often has 6 electrons (happy)

Answer: E (BCl₃)

300

Question #14

  • Different atoms + asymmetry → polar

Answer: A

300

Question #23

  • Total = 6 regions → 4 bonds + 2 lone pairs

Answer: B

300

Question #28

Bond order = (bonding - antibonding)/2

= 0 

Answer: A

400

Question #2

Answer: D (FO₄⁻)

Oxyanion pattern:

  • hypo- → least O
  • -ite → less O
  • -ate → more O
  • per- → MOST O

So:

  • FO⁻ → hypo
  • FO₂⁻ → ite
  • FO₃⁻ → ate
  • FO₄⁻ → per-ate 
400

Question #17

Formal charge = valence - nonbonding - 1/2(bonding) 


For SCN⁻ → N = -2

Answer: A

400

Question #15

  • 3 equal resonance structures

Answer: B

400

Question #24

  • Single = 1 sigma
  • Double = 1 sigma + 1 pi
  • Triple = 1 sigma + 2 pi

Answer: D

400

Question #29

  • All electrons paired → diamagnetic

Answer: A

500

Question #3 and #4

Answer: C

Steps:

  1. Selenium (Se) is in group 16 → 6 valence electrons
  2. Se²⁻ → gains 2 electrons → 8 total electrons
  3. Draw full octet (8 dots) around Se

Choose the diagram showing 8 dots + 2− charge

Answer: A

  1. Ca → Ca²⁺
  2. Cl → Cl⁻
  3. Balance charges:
    • Need 2 Cl⁻ to balance Ca²⁺

→ CaCl₂

Correct diagram shows:

  • Ca²⁺ (no dots)
  • 2 Cl⁻ ions (full octets)
500

Question #5 and #6 (nomenclature)

Answer: C (tin(IV) sulfate)

  1. Sulfate = SO₄²⁻
  2. Two sulfates = total -4 charge
  3. Sn must be +4

→ tin(IV)

Answer: C (difluorine monoxide)

This is molecular (nonmetal + nonmetal) → use prefixes:

  • 2 F → di-fluorine
  • 1 O → monoxide
500

Question #16

  • Trigonal planar → 120°

Answer: C

500

Question #25

  • Side-by-side p orbital overlap

Answer: E

500

Question #7 and #8 (Extra)

Answer: C (Mg₃N₂)

  1. Mg → Mg²⁺
  2. N → N³⁻

Balance charges:

  • LCM of 2 and 3 = 6
  • 3 Mg²⁺ = +6
  • 2 N³⁻ = -6

→ Mg₃N₂ (criss-cross the charges)


Answer: B (sulfuric acid)

Rules for acids:

  • -ate → -ic acid
  • sulfate (SO₄²⁻) → sulfuric acid

✔ H₂SO₄ = sulfuric acid

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