Question 1

Which of the following electron configurations correctly represents the ground state of a phosphorus atom (atomic number 15) according to the Aufbau principle, Pauli exclusion principle, and Hund's rule?

Accepted Answer

$1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^3$

Question 2

Which statement best explains why oxygen is paramagnetic?

Accepted Answer

Oxygen has two unpaired electrons in its $2p$ orbitals.

Question 3

Which of the following elements has the highest first ionization energy?

Accepted Answer

Neon ($Ne$)

Question 4

A student mixes 50.0 mL of 0.200 M $HCl$ with 50.0 mL of 0.200 M $NaOH$. What is the final concentration of $Cl^-$ ions in the solution after the reaction is complete?

Accepted Answer

$0.100\ \mathrm{M}$

Question 5

Which of the following best describes the difference between a strong acid and a weak acid in aqueous solution?

Accepted Answer

A strong acid completely ionizes in water, while a weak acid only partially ionizes.

Question 6

Which quantum numbers are needed to uniquely identify an electron in an atom?

Accepted Answer

Principal ($n$), angular momentum ($l$), magnetic ($m_l$), and spin ($m_s$) quantum numbers

Question 7

Which of the following is the correct net ionic equation for the reaction between $AgNO_3$ and $NaCl$ in aqueous solution?

Accepted Answer

$Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)$

Question 8

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

Accepted Answer

It donates electrons and is itself oxidized.

Question 9

Calculate the molarity of a solution prepared by dissolving 5.00 g of $NaCl$ (molar mass = $58.44\ \mathrm{g/mol}$) in enough water to make $250.0\ \mathrm{mL}$ of solution.

Accepted Answer

$0.342\ \mathrm{M}$

Question 10

Which of the following statements about electromagnetic radiation is correct?

Accepted Answer

The energy of a photon is inversely proportional to its wavelength.

Question 11

A sample of $CaCO_3$ reacts with excess $HCl$ to produce $CO_2$ gas. If $10.0\ \mathrm{g}$ of $CaCO_3$ is used, how many moles of $CO_2$ are produced? ($M_{CaCO_3} = 100.09\ \mathrm{g/mol}$)

Accepted Answer

$0.100\ \mathrm{mol}$

Question 12

Which of the following elements is most likely to form a $2^+$ ion?

Accepted Answer

Magnesium ($Mg$)

Question 13

Which of the following is the correct balanced molecular equation for the reaction of $H_2SO_4$ with $Ba(OH)_2$?

Accepted Answer

$H_2SO_4 (aq) + Ba(OH)_2 (aq) \rightarrow BaSO_4 (s) + 2H_2O (l)$

Question 14

Which of the following best describes the Pauli exclusion principle?

Accepted Answer

No two electrons in the same atom can have the same set of four quantum numbers.

Question 15

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

Accepted Answer

$E = h 
u$

Question 16

Which of the following ions has the largest radius?

Accepted Answer

$S^{2-}$

Question 17

A solution is prepared by mixing $100.0\ \mathrm{mL}$ of $0.500\ \mathrm{M}$ $KBr$ with $400.0\ \mathrm{mL}$ of water. What is the final concentration of $KBr$?

Accepted Answer

$0.100\ \mathrm{M}$

Question 18

Which of the following is a correct statement about the emission spectrum of hydrogen?

Accepted Answer

It consists of discrete lines corresponding to specific electron transitions.

Question 19

Which of the following is the correct formula for calculating the heat of reaction ($q$) given mass ($m$), specific heat capacity ($c$), and temperature change ($\Delta T$)?

Accepted Answer

$q = mc\Delta T$

General Chemistry I: Study Guide for Exam 2 – Atomic Structure, Periodicity, Chemical Reactions, and Thermochemistry

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