Question 1

Which of the following best explains why the flame test for barium produces a green color while the flame test for strontium produces a red color?

Accepted Answer

Barium emits photons with higher energy than strontium, corresponding to shorter wavelengths.

Question 2

Given the quantum numbers $n=2$, $l=1$, $m_l=0$, $m_s=+\frac{1}{2}$, to which atomic orbital does this set belong?

Accepted Answer

2p$_z$ orbital

Question 3

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

Accepted Answer

Ca

Question 4

Which atom has a larger atomic radius, Sr or Br? Why?

Accepted Answer

Sr, because it is further down the group and has more electron shells.

Question 5

Which of the following ions has the most negative electron affinity?

Accepted Answer

F

Question 6

A solution is prepared by dissolving 14.2 g NaCl in enough water to make 250.0 mL of solution. What is the molarity of the solution? (Molar mass NaCl = 58.44 g/mol)

Accepted Answer

$0.970\ \mathrm{M}$

Question 7

If the freezing point depression constant for water is $1.86\ \mathrm{^	ext{o}C\ kg/mol}$, what is the freezing point of a solution made by dissolving $0.50$ mol of NaCl in $1.00$ kg of water? Assume complete dissociation.

Accepted Answer

$-3.72\ \mathrm{^	ext{o}C}$

Question 8

Which of the following molecules has a trigonal planar electron geometry according to VSEPR theory?

Accepted Answer

BF$_3$

Question 9

Which statement best describes the difference between the 2s and 2p orbitals in a hydrogen atom?

Accepted Answer

The 2s orbital has a radial node, while the 2p orbital does not.

Question 10

Which of the following best explains why the ionization energy of sulfur is less than that of oxygen?

Accepted Answer

Sulfur's valence electrons are further from the nucleus, reducing the effective nuclear attraction.

Question 11

Which of the following is the correct electron configuration for Ni (Nickel, atomic number 28)?

Accepted Answer

$[\mathrm{Ar}]\ 3d^8\ 4s^2$

Question 12

Which of the following molecules is polar?

Accepted Answer

H$_2$O

Question 13

Which of the following best describes the effect of adding a non-volatile solute to a solvent?

Accepted Answer

It increases the boiling point and decreases the freezing point of the solvent.

Question 14

Given the following data, calculate the lattice energy for the formation of 1 mole of KCl using Hess's Law:

Ionization Energy of K: $+419\ \mathrm{kJ}$
Electron Affinity of Cl: $-349\ \mathrm{kJ}$
Dissociation Energy of Cl$_2$: $+242\ \mathrm{kJ}$
Enthalpy of Sublimation of K: $+89\ \mathrm{kJ}$
Bond Energy of KCl: $-715\ \mathrm{kJ}$

Accepted Answer

$-715\ \mathrm{kJ}$

Question 15

Which of the following best describes the geometry and bond angle of CH$_4$ according to VSEPR theory?

Accepted Answer

Tetrahedral, $109.5^	ext{o}$

Question 16

Which of the following statements about the periodic trend in metallic character is correct?

Accepted Answer

Metallic character increases down a group and decreases across a period.

Question 17

Which of the following is the correct Lewis structure for CO$_2$?

Accepted Answer

O=C=O with two lone pairs on each oxygen atom.

Question 18

A solution is made by dissolving 5.4 g of boric acid (H$_3$BO$_3$, molar mass = 61.83 g/mol) in 100.0 g of water. What is the molality of the solution?

Accepted Answer

$0.087\ \mathrm{mol/kg}$

Question 19

Which of the following best describes the effect of electron shielding on atomic radius?

Accepted Answer

Increased electron shielding increases atomic radius.

Question 20

Which of the following is the correct set of quantum numbers for a 3p$_x$ electron?

Accepted Answer

$n=3$, $l=1$, $m_l=+1$, $m_s=+\frac{1}{2}$

General Chemistry Exam 3 Study Guide: Atomic Structure, Periodic Trends, Bonding, and Solutions

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