Q: Which statement best explains why the first ionization energy increases across a period from left to right?

Effective nuclear charge ($$Z_{\text{eff}}) $$increases, pulling electrons closer to the nucleus.

Q: Calculate the mass percent of oxygen in H$$_2O. ($$Atomic masses: H = 1.01 g/mol, O = 16.00 g/mol)

$$\frac{16.00}{2 \times 1.01 + 16.00} \times 100\% = 88.8\%$$

Q: A sample contains 0.50 mol of NaCl. What is its mass? (Na = 22.99 g/mol, Cl = 35.45 g/mol)

$$0.50 \times (22.99 + 35.45) = 29.22\ \text{g}$$

Q: Which of the following best describes the trend in atomic radius across a period from left to right?

Atomic radius decreases due to increasing $$Z_{\text{eff}}.$$

Question 1

Which of the following ions has the electron configuration $$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^6$$?

Accepted Answer

Cl$$^-$$

Question 2

Which of the following elements is expected to be paramagnetic in its ground state?

Accepted Answer

Oxygen (O)

Question 3

Which statement best explains why the first ionization energy increases across a period from left to right?

Accepted Answer

Effective nuclear charge ($$Z_{	ext{eff}}) $$increases, pulling electrons closer to the nucleus.

Question 4

Given the following successive ionization energies (in kJ/mol): 578, 1817, 2745, 11600, which element is most likely represented?

Accepted Answer

Magnesium (Mg)

Question 5

Which compound is most likely to be ionic based on the elements involved?

Accepted Answer

NaCl

Question 6

What is the correct name for the compound Fe$$_2(SO$_4$$)$$_3$$?

Accepted Answer

Iron(III) sulfate

Question 7

Calculate the mass percent of oxygen in H$$_2O. ($$Atomic masses: H = 1.01 g/mol, O = 16.00 g/mol)

Accepted Answer

$$\frac{16.00}{2 	imes 1.01 + 16.00} 	imes 100\% = 88.8\%$$

Question 8

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 9

Which of the following bonds is the most polar, based on electronegativity differences?

Accepted Answer

H–F

Question 10

Which molecule has a central atom with sp$$^3$$ hybridization?

Accepted Answer

CH$$_4$$

Question 11

Which of the following molecules is nonpolar, despite having polar bonds?

Accepted Answer

CO$$_2$$

Question 12

What is the formal charge on the central atom in the best Lewis structure for NO$$_3^-$$?

Accepted Answer

0

Question 13

Which of the following molecules exhibits resonance?

Accepted Answer

O$$_3$$

Question 14

Which of the following statements about bond energy and bond length is correct?

Accepted Answer

Triple bonds are shorter and stronger than single bonds.

Question 15

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

Accepted Answer

Octahedral, octahedral

Question 16

Which of the following best describes the theoretical basis for Valence Bond (VB) Theory?

Accepted Answer

Covalent bonds form when atomic orbitals overlap and electrons are shared.

Question 17

How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in the molecule C$$_2H$_4 ($$ethylene)?

Accepted Answer

5 $$\sigma$$, 1 $$\pi$$

Question 18

Which of the following is an exception to the octet rule due to an expanded octet?

Accepted Answer

PCl$$_5$$

Question 19

A sample contains 0.50 mol of NaCl. What is its mass? (Na = 22.99 g/mol, Cl = 35.45 g/mol)

Accepted Answer

$$0.50 	imes (22.99 + 35.45) = 29.22\ 	ext{g}$$

Question 20

Which of the following best describes the trend in atomic radius across a period from left to right?

Accepted Answer

Atomic radius decreases due to increasing $$Z_{	ext{eff}}.$$

General Chemistry Study Guide: Periodic Properties, Molecules & Compounds, and Chemical Bonding

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