Question 1

Which of the following correctly describes the three main subatomic particles in an atom, including their charge and location?

Accepted Answer

Proton: positive, in the nucleus; Neutron: neutral, in the nucleus; Electron: negative, outside the nucleus

Question 2

Which of the following is the correctly balanced chemical equation for the reaction of hydrogen gas with oxygen gas to form water?

Accepted Answer

$\mathrm{2H_2 + O_2 \rightarrow 2H_2O}$

Question 3

Why is it important to balance chemical equations?

Accepted Answer

To satisfy the law of conservation of mass

Question 4

A student mixes 2.0 L of water with 0.5 mol of NaCl. What is the molarity of the resulting solution?

Accepted Answer

$0.25\ \mathrm{M}$

Question 5

Which of the following best describes the location of electrons in an atom?

Accepted Answer

Electrons are located in a cloud surrounding the nucleus

Question 6

Given the unbalanced equation: $\mathrm{H_2 + O_2 \rightarrow H_2O}$, what is the minimum number of $\mathrm{H_2}$ molecules needed to completely react with one $\mathrm{O_2}$ molecule?

Accepted Answer

2

Question 7

Which of the following statements about the nucleus of an atom is correct?

Accepted Answer

The nucleus contains protons and neutrons

Question 8

A chemist wants to prepare 1.0 L of a 0.5 M NaCl solution. How many moles of NaCl are required?

Accepted Answer

0.5 moles

Question 9

Which of the following is a correct statement about the charges of subatomic particles?

Accepted Answer

Protons are positively charged, neutrons are neutral, electrons are negatively charged

Question 10

If a chemical equation is not balanced, which of the following is most likely to be violated?

Accepted Answer

Law of conservation of mass

Question 11

Which of the following best represents the balanced equation for the reaction of sodium chloride with water?

Accepted Answer

$\mathrm{NaCl (s) \rightarrow Na^+ (aq) + Cl^- (aq)}$

Question 12

A solution is made by dissolving 0.25 mol of NaCl in enough water to make 0.5 L of solution. What is the molarity of the solution?

Accepted Answer

$0.5\ \mathrm{M}$

Question 13

Which of the following is NOT a reason for balancing chemical equations?

Accepted Answer

To change the identity of the elements involved

Question 14

Which of the following best describes the process of dissolving NaCl in water?

Accepted Answer

NaCl dissociates into $\mathrm{Na^+}$ and $\mathrm{Cl^-}$ ions

Question 15

A reaction produces 36 grams of water ($\mathrm{H_2O}$). How many moles of water is this? (Molar mass of $\mathrm{H_2O}$ = 18 g/mol)

Accepted Answer

2 moles

Question 16

Which of the following is true about the conservation of mass in a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products

Question 17

Which of the following is the correct formula for calculating molarity ($M$)?

Accepted Answer

$M = \dfrac{	ext{moles of solute}}{	ext{volume of solution in liters}}$

Question 18

If you have 1.0 mol of $\mathrm{H_2}$ and 1.0 mol of $\mathrm{O_2}$, how many moles of $\mathrm{H_2O}$ can be formed according to the balanced equation $\mathrm{2H_2 + O_2 \rightarrow 2H_2O}$?

Accepted Answer

2.0 mol

Question 19

Which of the following best explains why electrons are not found in the nucleus?

Accepted Answer

Electrons occupy energy levels outside the nucleus due to their negative charge

Question 20

A solution contains 0.1 mol of NaCl dissolved in 0.2 L of water. What is the molarity of the solution?

Accepted Answer

$0.5\ \mathrm{M}$

Atoms, Subatomic Particles, and Chemical Equations – Guided Study

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