Q: Convert 0.0056 kilometers to centimeters. (1 km = 1000 m, 1 m = 100 cm)

$$0.0056\ \mathrm{km} \times \frac{1000\ \mathrm{m}}{1\ \mathrm{km}} \times \frac{100\ \mathrm{cm}}{1\ \mathrm{m}} = 560\ \mathrm{cm}$$

Q: A neutral atom of chlorine has an atomic number of 17 and a mass number of 35. How many neutrons does it have?

$$\text{Number of neutrons} = 35 - 17 = 18$$

Q: How many molecules are present in 0.25 moles of water ($$\mathrm{H_2O}$$)? ($$N_A = 6.022 \times 10$$^{23}$$\ \mathrm{mol}^{-1})$$

$$0.25 \times 6.022 \times 10$$^{23}$$ = 1.51 \times 10$$^{23}$$ molecules

Q: A solution is prepared by dissolving 10.0 g of NaCl in enough water to make 250 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

$$\text{Molarity} = \frac{10.0\ \mathrm{g}}{58.44\ \mathrm{g/mol}} \div 0.250\ \mathrm{L} = 0.684\ \mathrm{M}$$

Question 1

A sample of a metal has a mass of 45.0 g and a volume of 15.0 mL. What is the density of the metal?

Accepted Answer

$$d = \frac{m}{V} = \frac{45.0\ \mathrm{g}}{15.0\ \mathrm{mL}} = 3.00\ \mathrm{g/mL}$$

Question 2

Which of the following processes is endothermic?

Accepted Answer

Sublimation of dry ice (solid CO$$_2)$$

Question 3

A student measures the mass of a sample as 12.30 g and its volume as 4.0 mL. How many significant figures should the calculated density have?

Accepted Answer

2 significant figures

Question 4

Which of the following is a chemical change?

Accepted Answer

Rusting of iron

Question 5

Convert 0.0056 kilometers to centimeters. (1 km = 1000 m, 1 m = 100 cm)

Accepted Answer

$$0.0056\ \mathrm{km} 	imes \frac{1000\ \mathrm{m}}{1\ \mathrm{km}} 	imes \frac{100\ \mathrm{cm}}{1\ \mathrm{m}} = 560\ \mathrm{cm}$$

Question 6

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 7

A neutral atom of chlorine has an atomic number of 17 and a mass number of 35. How many neutrons does it have?

Accepted Answer

$$	ext{Number of neutrons} = 35 - 17 = 18$$

Question 8

Which of the following compounds is named correctly?

Accepted Answer

NaCl: Sodium chloride

Question 9

How many molecules are present in 0.25 moles of water ($$\mathrm{H_2O}$$)? ($$N_A = 6.022 	imes 10$$^{23}$$\ \mathrm{mol}^{-1})$$

Accepted Answer

$$0.25 	imes 6.022 	imes 10$$^{23}$$ = 1.51 	imes 10$$^{23}$$ molecules

Question 10

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of NaCl and AgNO$$_3$$?

Accepted Answer

$$\mathrm{Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)}$$

Question 11

A reaction has $$\Delta H = -125\ \mathrm{kJ}. $$Which statement is true?

Accepted Answer

The reaction is exothermic and releases heat.

Question 12

Which of the following molecules is polar?

Accepted Answer

H$$_2O$$

Question 13

Which of the following statements about intermolecular forces is correct?

Accepted Answer

Hydrogen bonding is stronger than dipole-dipole forces.

Question 14

A solution is prepared by dissolving 10.0 g of NaCl in enough water to make 250 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$	ext{Molarity} = \frac{10.0\ \mathrm{g}}{58.44\ \mathrm{g/mol}} \div 0.250\ \mathrm{L} = 0.684\ \mathrm{M}$$

Question 15

Which of the following solutions will have the lowest freezing point?

Accepted Answer

0.20 m Na$$_2SO$_4$$

Question 16

Which of the following is a strong acid?

Accepted Answer

HCl

Question 17

A buffer solution can be made by mixing:

Accepted Answer

A weak acid and its conjugate base

Question 18

What is the pH of a solution with $$[H_3O^+] = 1.0 	imes 10$$^{-4}$$\ \mathrm{M}$$?

Accepted Answer

$$\mathrm{pH} = -\log(1.0 	imes 10$$^{-4}$$) = 4.00$$

Question 19

Which of the following nuclear reactions represents beta decay?

Accepted Answer

$$^{14}_{6}\mathrm{C} \$$rightarrow ^{14}$$_{7}\mathrm{N} $$+ ^{0}$$_{-1}\beta$$

ACS Final Exam Review: Introductory Chemistry Study Guide

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