Q: A solution is prepared by dissolving 10.0 g of NaCl in 100.0 g of water. What is the mass percent of NaCl in the solution?

$$\frac{10.0}{110.0} \times 100 = 9.09\%$$

Q: A sample contains 80% $$^{35}Cl $$and 20% $$^{37}Cl. $$What is the average atomic mass of chlorine? (Atomic masses: $$^{35}Cl = 34.97 $$amu, $$^{37}Cl = 36.97 $$amu)

$$(0.80 \times 34.97) + (0.20 \times 36.97) = 35.37$$ amu

Q: A student needs to prepare 250 mL of a 0.5 M NaCl solution. How many grams of NaCl are required? ($$M_{NaCl} = 58.44 g/$$mol)

$$0.5 \times 0.250 \times 58.44 = 7.305 g$$

Question 1

Which of the following is an example of a homogeneous mixture?

Accepted Answer

A glass of saltwater

Question 2

Which statement best describes a chemical change?

Accepted Answer

Iron rusting in the presence of oxygen

Question 3

A student measures the mass of a sample as 12.34 g, 12.36 g, and 12.35 g in three trials. The true mass is 12.50 g. Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 4

Which of the following is the correct number of significant figures in the measurement 0.00450 m?

Accepted Answer

3

Question 5

Convert 25.0 °C to Kelvin using the correct formula.

Accepted Answer

$$K = ^\circ C + 273.15$$

Question 6

A solution is prepared by dissolving 10.0 g of NaCl in 100.0 g of water. What is the mass percent of NaCl in the solution?

Accepted Answer

$$\frac{10.0}{110.0} 	imes 100 = 9.09\%$$

Question 7

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 8

Given the atomic number of magnesium is 12, how many electrons does a neutral magnesium atom have?

Accepted Answer

12

Question 9

Which subatomic particle has a negative charge and relatively no mass?

Accepted Answer

Electron

Question 10

A sample contains 80% $$^{35}Cl $$and 20% $$^{37}Cl. $$What is the average atomic mass of chlorine? (Atomic masses: $$^{35}Cl = 34.97 $$amu, $$^{37}Cl = 36.97 $$amu)

Accepted Answer

$$(0.80 	imes 34.97) + (0.20 	imes 36.97) = 35.37$$ amu

Question 11

Which group in the periodic table contains the noble gases?

Accepted Answer

Group 18

Question 12

What is the empirical formula for a compound with a molecular formula of $$C_6H_{12}O_6$?

Accepted Answer

$$CH_2O$$

Question 13

Which of the following is a functional group found in carboxylic acids?

Accepted Answer

-COOH

Question 14

A student needs to prepare 250 mL of a 0.5 M NaCl solution. How many grams of NaCl are required? ($$M_{NaCl} = 58.44 g/$$mol)

Accepted Answer

$$0.5 	imes 0.250 	imes 58.44 = 7.305 g$$

Question 15

Which of the following best describes the difference between accuracy and precision?

Accepted Answer

Accuracy is how close measurements are to the true value; precision is how close measurements are to each other.

Question 16

Which of the following is NOT a physical change?

Accepted Answer

Burning gasoline in a car engine

Question 17

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula?

Accepted Answer

$$CH_2O$$

Question 18

Which statement about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 19

Which of the following ions has a +2 charge?

Accepted Answer

$$Mg^{2+}$$

General Chemistry Exam 1 Review: Key Concepts and Takeaways

Study Guide - Practice Questions

Study Guide - Flashcards