Q: Which of the following is the correct formula for calculating the number of moles from a given mass?

$$\text{moles} = \dfrac{\text{mass}}{\text{molar mass}}$$

Q: Which of the following is the correct formula for calculating the concentration of a solution in molarity ($$M$$)?

$$M = \dfrac{\text{moles of solute}}{\text{volume (L)}}$$

Question 1

Which of the following best describes the difference between ionic and molecular (covalent) compounds?

Accepted Answer

Ionic compounds consist of metals and nonmetals, while molecular compounds consist only of nonmetals.

Question 2

A student mixes hydrochloric acid ($$\mathrm{HCl}) $$with sodium hydroxide ($$\mathrm{NaOH}) in a $$beaker. Which type of chemical reaction is occurring?

Accepted Answer

Neutralization

Question 3

Which of the following is the correct formula for calculating the number of moles from a given mass?

Accepted Answer

$$	ext{moles} = \dfrac{	ext{mass}}{	ext{molar mass}}$$

Question 4

Which statement best explains why sodium ($$\mathrm{Na}) $$reacts vigorously with water?

Accepted Answer

Sodium has a low ionization energy, allowing it to easily lose an electron and form $$\mathrm{Na^+}$$ ions.

Question 5

A solution has a pH of 3. Which of the following best describes this solution?

Accepted Answer

It is acidic.

Question 6

Which of the following is the correct balanced equation for the reaction between potassium ($$\mathrm{K}) $$and chlorine gas ($$\mathrm{Cl_2$}$$)?

Accepted Answer

$$\mathrm{2K + Cl_2$ \rightarrow 2KCl}$$

Question 7

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

A catalyst speeds up the reaction by lowering the activation energy.

Question 8

A patient is given a solution containing $$0.9\%$$ sodium chloride ($$\mathrm{NaCl}) $$intravenously. What type of solution is this relative to the cells in the body?

Accepted Answer

Isotonic

Question 9

Which of the following is the correct formula for calculating the concentration of a solution in molarity ($$M$$)?

Accepted Answer

$$M = \dfrac{	ext{moles of solute}}{	ext{volume (L)}}$$

Question 10

Which of the following best explains why water ($$\mathrm{H_2O}) is $$considered a polar molecule?

Accepted Answer

Water has a bent shape and an uneven distribution of electron density.

Question 11

A sample contains $$75.0$$ grams of glucose ($$\mathrm{C_6H_{12}O_6$}). $$What is the number of moles present? (Molar mass of glucose = $$180.0 g/$$mol)

Accepted Answer

$$0.42$$ moles

Question 12

Which of the following is a property of acids?

Accepted Answer

They react with metals to produce hydrogen gas.

Question 13

Which of the following is the correct net ionic equation for the reaction between hydrochloric acid ($$\mathrm{HCl}) $$and sodium hydroxide ($$\mathrm{NaOH}$$)?

Accepted Answer

$$\mathrm{H^+ (aq) + OH^- (aq) \rightarrow H_2O (l)}$$

Question 14

Which of the following best describes the process of osmosis?

Accepted Answer

Movement of solvent molecules from high to low concentration across a semipermeable membrane.

Question 15

A chemical reaction has $$\Delta H \u003c 0. $$What does this indicate about the reaction?

Accepted Answer

The reaction is exothermic and releases heat.

Question 16

Which of the following is the correct formula for calculating the percent composition of an element in a compound?

Accepted Answer

$$\dfrac{	ext{molar mass of element}}{	ext{molar mass of compound}} 	imes 100\%$$

Question 17

A nurse needs to prepare $$500 mL of a$$ $$0.2 M $$sodium chloride ($$\mathrm{NaCl}) $$solution. How many moles of $$\mathrm{NaCl}$$ are required?

Accepted Answer

$$0.1$$ moles

Question 18

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have full valence electron shells.

Question 19

Which of the following is the correct formula for calculating the energy of a photon?

Accepted Answer

$$E = h 
u$$

Question 20

A student dissolves $$10.0 g of $$sodium chloride ($$\mathrm{NaCl}) in$$ $$250 mL of $$water. What is the molarity of the solution? (Molar mass of $$\mathrm{NaCl}$$ = $$58.5 g/$$mol)

Accepted Answer

$$0.68 M$$

Fundamental Concepts in GOB Chemistry: Matter, Energy, Acids & Bases, and Chemical Calculations

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