Q: A 0.500 L solution contains 0.250 mol NaOH. What is the molarity of the solution?

$$M = \frac{0.250\ \text{mol}}{0.500\ \text{L}} = 0.500\ \text{M}$$

Q: Which of the following reactions is a redox reaction?

$$\text{H}_2 + \text{Cl}_2 \rightarrow 2\text{HCl}$$

Q: A 2.00 g sample of magnesium reacts with excess oxygen to form magnesium oxide. How many moles of MgO are produced? (Mg: 24.3 g/mol, O: 16.0 g/mol)

$$\text{mol Mg} = \frac{2.00}{24.3} = 0.0823$$; $$\text{mol MgO} = 0.0823$$

Question 1

Which of the following statements best describes a pure substance?

Accepted Answer

A material with a fixed composition that cannot be separated by physical means.

Question 2

A sample of gas is measured at 25°C. What is this temperature in Kelvin?

Accepted Answer

$$K = 25 + 273.15 = 298.15$$

Question 3

Which experiment led to the discovery of the electron?

Accepted Answer

Thomson's cathode ray tube experiment

Question 4

Given the isotope symbol $$^{37}_{17}	ext{Cl}$$, what is the number of neutrons in this isotope?

Accepted Answer

20

Question 5

Which of the following compounds is an electrolyte when dissolved in water?

Accepted Answer

NaCl (sodium chloride)

Question 6

A 0.500 L solution contains 0.250 mol NaOH. What is the molarity of the solution?

Accepted Answer

$$M = \frac{0.250\ 	ext{mol}}{0.500\ 	ext{L}} = 0.500\ 	ext{M}$$

Question 7

Which of the following reactions is a redox reaction?

Accepted Answer

$$	ext{H}_2 + 	ext{Cl}_2 ightarrow 2	ext{HCl}$$

Question 8

A 2.00 g sample of magnesium reacts with excess oxygen to form magnesium oxide. How many moles of MgO are produced? (Mg: 24.3 g/mol, O: 16.0 g/mol)

Accepted Answer

$$	ext{mol Mg} = \frac{2.00}{24.3} = 0.0823$$; $$	ext{mol MgO} = 0.0823$$

Question 9

Which gas law explains why a balloon shrinks when placed in a freezer?

Accepted Answer

Charles's Law ($$\frac{V_1$}{T_1$} = \frac{V_2$}{T_2$})$$

Question 10

A 3.0 L container holds a mixture of gases: 1.0 mol O$$_2$$, 2.0 mol N$$_2$$, and 1.0 mol CO$$_2. $$What is the mole fraction of N$$_2$$?

Accepted Answer

$$\chi_{N_2$} = \frac{2.0}{1.0 + 2.0 + 1.0} = \frac{2.0}{4.0} = 0.50$$

Question 11

Which of the following statements about energy changes in a bomb calorimeter is correct?

Accepted Answer

The reaction occurs at constant volume, and the measured heat equals the change in internal energy ($$\Delta U).$$

Question 12

Which equation correctly relates the heat absorbed by a substance to its mass, specific heat, and temperature change?

Accepted Answer

$$q = m \cdot c \cdot \Delta T$$

Question 13

Which quantum number determines the shape of an orbital?

Accepted Answer

Angular momentum quantum number ($$l)$$

Question 14

What is the wavelength of light emitted when an electron in a hydrogen atom transitions from $$n=3 to$$ $$n=2$$? (Use $$E = -2.18 	imes 10$$^{-18}$$ \left( \frac{1}{n^2$} ight) J $$and $$E = h
u = \frac{hc}{\lambda}$$; $$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$\lambda = 656\ 	ext{nm}$$

Question 15

Which element has the highest first ionization energy?

Accepted Answer

Fluorine (F)

Question 16

Which of the following molecules is polar?

Accepted Answer

NH$$_3$$

Question 17

Which compound has the greatest lattice energy?

Accepted Answer

MgO

Question 18

According to VSEPR theory, what is the electron geometry and molecular shape of water (H$$_2O$$)?

Accepted Answer

Electron geometry: tetrahedral; molecular shape: bent

Question 19

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

Accepted Answer

BF$$_3$$

General Chemistry I: Comprehensive Study Notes (Chapters 1–11)

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