Q: How many molecules of CO$_2$ are in 0.0180 moles of CO$_2$? Use Avogadro's number $6.022 \times 10^{23}$ molecules/mol.

$1.08 \times 10^{22}$ molecules of CO$_2$

Question 1

What is the charge on Sn in the ionic compound SnO?

Accepted Answer

+2

Question 2

Which is the strongest type of intermolecular force present between molecules of liquid NF$_3$?

Accepted Answer

dipole-dipole attractions

Question 3

Which of the following covalent bonds is considered non-polar?

I. C-H
II. O-O
III. C-S
IV. F-F

Accepted Answer

only II and IV

Question 4

Given the balanced equation:

$4\mathrm{NH}_3 (g) + 3\mathrm{O}_2 (g) \rightarrow 2\mathrm{N}_2 (g) + 6\mathrm{H}_2\mathrm{O} (g)$

How many moles of NH$_3$ are required to react with 2.00 mol O$_2$?

Accepted Answer

2.67 mol NH$_3$

Question 5

Which molecule is predicted to have the highest boiling point?

Accepted Answer

CH$_3$OH

Question 6

How many molecules of CO$_2$ are in 0.0180 moles of CO$_2$?

Use Avogadro's number $6.022 	imes 10^{23}$ molecules/mol.

Accepted Answer

$1.08 	imes 10^{22}$ molecules of CO$_2$

Question 7

What is the formula of an ionic compound formed from calcium and hydroxide ions?

Accepted Answer

Ca(OH)$_2$

Question 8

How many total bonding electrons are present in the Lewis structure of hydrazine (H$_2$N–NH$_2$)?

Accepted Answer

8 total bonding electrons

Question 9

Which of the following has a predicted bond angle of 109.5$^{\circ}$?

I. trigonal planar, bent
II. tetrahedral, trigonal pyramidal
III. linear, linear
IV. tetrahedral, bent

Accepted Answer

II and IV

Question 10

Which of the following statements best describes why metals become cations?

Accepted Answer

Metals have lower ionization energies, making it more likely to lose electrons.

Question 11

Which of the following molecules does NOT have a triple bond present in the correct Lewis structure?

Accepted Answer

CO

Question 12

How many picometers (pm) are there in 2.56 mm?

(1 mm = $1 	imes 10^6$ pm)

Accepted Answer

$2.56 	imes 10^6$ pm

Question 13

How many total electrons does N$^{3-}$ have?

Accepted Answer

10

Question 14

Copper(II) nitrate is used in chemistry labs. What is its chemical formula?

Accepted Answer

Cu(NO$_3$)$_2$

Question 15

Which of the following best describes Ni(s) in the following chemical equation?

$\mathrm{Ni}(s) \rightarrow \mathrm{Ni}^{2+}(aq) + 2e^-$

Accepted Answer

Ni(s) is oxidized

Question 16

What type of classification best characterizes the following reaction?

$2\mathrm{HBr}(g) \rightarrow \mathrm{H}_2(g) + \mathrm{Br}_2(g)$

Accepted Answer

decomposition reaction

Question 17

What is the correct number of significant figures in the calculation below?

$\dfrac{12.315 	imes 6.085}{(29 + 0.9) 	imes 7.243} = 0.084962$

Accepted Answer

3

Question 18

How many liters are in $0.030\ \mathrm{m}^3$?

Accepted Answer

30.0 L

Question 19

A student measures the length of a pencil using a ruler marked in centimeters. The pencil extends from 0.0 cm to 15.55 cm. What is the length of the pencil?

Accepted Answer

15.55 cm

Question 20

How many chlorine (Cl) atoms are in a 15 gram sample of CaCl$_2$?

(Molar mass CaCl$_2$ = 110.98 g/mol, Avogadro's number = $6.022 	imes 10^{23}$)

Accepted Answer

$1.63 	imes 10^{23}$ Cl atoms

CHEM 1070 – General Chemistry I: Practice Exam Study Notes

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