Q: How many molecules are present in $2.00$ moles of $CO_2$? (Avogadro's number $= 6.022 \times 10^{23}$ molecules/mol)

$1.20 \times 10^{24}$ molecules

Question 1

Which of the following best describes how ions are held together in an ionic bond?

Accepted Answer

By the electrostatic attraction between oppositely charged ions

Question 2

Given an element in Group 2, Period 3 of the periodic table, which of the following is correct about its classification and likely ion formed?

Accepted Answer

It is a metal and forms a $+2$ ion

Question 3

Which of the following compounds is named correctly according to ionic compound naming rules?

Accepted Answer

NaCl: Sodium chloride

Question 4

Which of the following best describes the shape and bond angle of methane ($CH_4$) according to VSEPR theory?

Accepted Answer

Tetrahedral, $109.5^	ext{o}$

Question 5

Which of the following molecules is polar due to its shape and bond polarity?

Accepted Answer

H$_2$O

Question 6

How many molecules are present in $2.00$ moles of $CO_2$? (Avogadro's number $= 6.022 	imes 10^{23}$ molecules/mol)

Accepted Answer

$1.20 	imes 10^{24}$ molecules

Question 7

What is the mass of $0.50$ moles of sodium chloride ($NaCl$)? (Molar mass of $NaCl = 58.44$ g/mol)

Accepted Answer

$29.22$ g

Question 8

A sample of nitrogen gas ($N_2$) occupies $44.8$ L at STP. How many moles of $N_2$ are present? (At STP, $1$ mole of gas occupies $22.4$ L)

Accepted Answer

$2.00$ moles

Question 9

What is the percent composition by mass of oxygen in water ($H_2O$)? (Molar mass: $H = 1.01$ g/mol, $O = 16.00$ g/mol)

Accepted Answer

$88.8\%$

Question 10

Which of the following is a balanced chemical equation for the combustion of methane ($CH_4$)?

Accepted Answer

$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$

Question 11

In the reaction $Zn + CuSO_4 \rightarrow ZnSO_4 + Cu$, which species is oxidized?

Accepted Answer

$Zn$

Question 12

Which of the following best describes a double-replacement reaction?

Accepted Answer

Two compounds exchange ions to form two new compounds

Question 13

If $4.00$ g of hydrogen reacts with $32.0$ g of oxygen to form water, what is the limiting reactant? (Molar mass: $H_2 = 2.02$ g/mol, $O_2 = 32.00$ g/mol)

Accepted Answer

Neither, they are in stoichiometric proportion

Question 14

A reaction has a theoretical yield of $10.0$ g, but only $7.5$ g of product is obtained. What is the percent yield?

Accepted Answer

$75\%$

Question 15

Which of the following best describes the role of the oxidizing agent in a redox reaction?

Accepted Answer

It gains electrons and is reduced

Question 16

How many grams of $CO_2$ are produced when $22.0$ g of $C_2H_6$ (ethane) is completely combusted? (Balanced equation: $2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O$, Molar mass: $C_2H_6 = 30.08$ g/mol, $CO_2 = 44.01$ g/mol)

Accepted Answer

$32.2$ g

Question 17

Which of the following is the correct formula for sulfuric acid?

Accepted Answer

$H_2SO_4$

Question 18

Which of the following statements about limiting reactants is correct?

Accepted Answer

The limiting reactant determines the maximum amount of product formed

Question 19

What is the mole ratio of $H_2$ to $O_2$ in the reaction $2H_2 + O_2 \rightarrow 2H_2O$?

Accepted Answer

$2:1$

Question 20

Which of the following best explains why ionic compounds tend to have high melting points?

Accepted Answer

They are held together by strong electrostatic forces between ions

General Chemistry Study Guide: Molecular Structure, Bonding, Moles, Chemical Reactions, and Stoichiometry

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