Q: A solution has $$ [H_3O^+] = 1.0 \times 10$$^{-4}$$ M. $$What is the pH of the solution?

$$ pH = -\log_{10}(1.0 \times 10$$^{-4}$$) = 4.00 $$

Question 1

Which of the following best describes the effect of increasing temperature on the rate of a chemical reaction, according to collision theory?

Accepted Answer

Increasing temperature increases the kinetic energy of molecules, leading to more frequent and energetic collisions, thus increasing the reaction rate.

Question 2

A reaction vessel contains the following equilibrium: $$ \mathrm{N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)} . If $$the pressure is increased by decreasing the volume, what will happen to the position of equilibrium according to LeChâtlier’s Principle?

Accepted Answer

The equilibrium will shift toward the products, $$ \mathrm{NH_3$} $$, because there are fewer moles of gas on the product side.

Question 3

Which of the following statements about the equilibrium constant $$ K  is $$correct?

Accepted Answer

A large $$ K $$ value ($$ K \gg 1 ) $$indicates that, at equilibrium, products are favored over reactants.

Question 4

Which of the following is the correct equilibrium constant expression for the reaction $$ \mathrm{2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)} $$?

Accepted Answer

$$ K = \frac{[SO_3$]^2}{[SO_2$]^2[O_2$]} $$

Question 5

A catalyst is added to a reaction at equilibrium. Which of the following best describes its effect?

Accepted Answer

It increases the rate at which equilibrium is reached but does not change the equilibrium constant or the position of equilibrium.

Question 6

Which of the following is a correct definition of a Bronsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($$ H^+ ) to $$another substance.

Question 7

Which of the following is a strong acid?

Accepted Answer

Hydrochloric acid ($$ \mathrm{HCl} )$$

Question 8

A solution has $$ [H_3O^+] = 1.0 	imes 10$$^{-4}$$  M. $$What is the pH of the solution?

Accepted Answer

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

Question 9

Which of the following combinations would create a buffer solution?

Accepted Answer

A solution of acetic acid ($$ \mathrm{CH_3COOH} ) $$and sodium acetate ($$ \mathrm{CH_3COONa} )$$

Question 10

Which of the following best describes what happens to the oxidation number of an element that is reduced in a redox reaction?

Accepted Answer

Its oxidation number decreases.

Question 11

In the reaction $$ \mathrm{Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)} $$, which species is the oxidizing agent?

Accepted Answer

$$ \mathrm{Cu$$^{2+}$$(aq)} $$

Question 12

Assign the oxidation number to sulfur in $$ \mathrm{SO_4$^{2-}} .$$

Accepted Answer

$$ +6 $$

Question 13

Which of the following nuclear equations correctly represents the alpha decay of $$ \mathrm{^{238}_{92}U} $$?

Accepted Answer

$$ \mathrm{^{238}_{92}U \$$rightarrow ^{234}$$_{90}Th $$+ ^{4}$$_{2}He} $$

Question 14

A radioactive isotope has a half-life of 10 years. If you start with a 100 g sample, how much will remain after 30 years?

Accepted Answer

12.5 g

Question 15

Which of the following best describes nuclear fusion?

Accepted Answer

The process in which two light nuclei combine to form a heavier nucleus, releasing energy.

Question 16

Which of the following is a real-world application of radioactivity in medicine?

Accepted Answer

Using $$ \mathrm{^{99m}Tc}  in $$imaging to diagnose organ function.

Question 17

Which of the following best describes the relationship between $$ [H_3O^+] $$ and $$ [OH^-]  in $$pure water at 25°C?

Accepted Answer

$$ [H_3O^+][OH^-] = 1.0 	imes 10$$^{-14}$$ $$

Question 18

Which of the following best explains why increasing the concentration of reactants generally increases the rate of a chemical reaction?

Accepted Answer

It increases the frequency of collisions between reactant molecules.

Question 19

Which of the following is the correct balanced equation for the neutralization of hydrochloric acid with sodium hydroxide?

Accepted Answer

$$ \mathrm{HCl(aq) + NaOH(aq) \rightarrow NaCl(aq) + H_2O(l)} $$

Comprehensive Guidance for Introductory Chemistry Exam Preparation (Modules 5–8)

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