$(0.7577 \times 34.969) + (0.2423 \times 36.966) = 35.45$ u

$M_1V_1 = M_2V_2$; $V_1 = \frac{0.50 \times 250}{2.0} = 62.5$ mL

$P = \frac{0.50 \times 0.0821 \times 300}{2.00} = 6.16$ atm

Question 1

Which of the following best describes the process for calculating the average atomic mass of an element with multiple isotopes?

Accepted Answer

Multiply the mass of each isotope by its percent abundance (as a decimal), sum the results.

Question 2

A sample of chlorine contains 75.77% $^{35}Cl$ (mass = 34.969 u) and 24.23% $^{37}Cl$ (mass = 36.966 u). What is the average atomic mass of chlorine?

Accepted Answer

$(0.7577 	imes 34.969) + (0.2423 	imes 36.966) = 35.45$ u

Question 3

Which electron configuration represents a neutral atom of magnesium?

Accepted Answer

$1s^2 2s^2 2p^6 3s^2$

Question 4

Which of the following best describes the difference between ionic and covalent compounds?

Accepted Answer

Ionic compounds transfer electrons, while covalent compounds share electrons.

Question 5

A student needs to prepare 250 mL of 0.50 M NaCl solution from a 2.0 M stock solution. What volume of the stock solution is required?

Accepted Answer

$M_1V_1 = M_2V_2$; $V_1 = \frac{0.50 	imes 250}{2.0} = 62.5$ mL

Question 6

Which of the following molecules has a trigonal planar shape?

Accepted Answer

BF$_3$

Question 7

Which of the following best explains why ionic compounds are typically solid at room temperature?

Accepted Answer

They have strong electrostatic forces between ions.

Question 8

Which of the following is the correct Lewis structure for CO$_2$?

Accepted Answer

O=C=O, with each O atom having two lone pairs.

Question 9

Which of the following is the correct formula for calculating the pressure of a gas using the ideal gas law?

Accepted Answer

$P = \frac{nRT}{V}$

Question 10

A 2.00 L container holds 0.50 mol of O$_2$ gas at 300 K. What is the pressure inside the container? ($R = 0.0821$ L·atm/mol·K)

Accepted Answer

$P = \frac{0.50 	imes 0.0821 	imes 300}{2.00} = 6.16$ atm

Question 11

Which of the following best describes the effect of increasing temperature on the rate of a chemical reaction?

Accepted Answer

The rate increases because more molecules have enough energy to react.

Question 12

Which of the following is the correct equation for the energy of a photon?

Accepted Answer

$E = h 
u$

Question 13

Which of the following statements about molecular dipoles is correct?

Accepted Answer

A molecule with a symmetrical shape may have no net dipole moment even if it has polar bonds.

Question 14

Which of the following is the correct formula for converting Celsius to Kelvin?

Accepted Answer

$K = ^\circ C + 273.15$

Question 15

Which of the following best describes the relationship between wavelength and frequency for electromagnetic waves?

Accepted Answer

As wavelength increases, frequency decreases.

Question 16

Which of the following is the correct empirical formula for a compound containing 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

CH$_2$O

Question 17

Which of the following best explains why water has a higher boiling point than methane?

Accepted Answer

Water forms hydrogen bonds, which are stronger than the London dispersion forces in methane.

Question 18

Which of the following is the correct equation for the combined gas law?

Accepted Answer

$\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}$

Question 19

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It decreases the activation energy.

Question 20

Which of the following is the correct relationship for percent composition by mass?

Accepted Answer

$\frac{	ext{mass of element}}{	ext{total mass of compound}} 	imes 100$

General Chemistry Exam Review Notes

Study Guide - Practice Questions