$$3 \times 10$$^{24}$$ molecules

Question 1

Which of the following statements best describes the octet rule as it applies to chemical bonding?

Accepted Answer

Atoms tend to gain or lose electrons to achieve the same number of electrons as a noble gas, usually eight in their valence shell.

Question 2

Which of the following compounds contains a polyatomic ion?

Accepted Answer

KNO$$_3$$

Question 3

What is the correct name for the compound Na$$_2SO$_4$$?

Accepted Answer

Sodium sulfate

Question 4

Which formula represents the chlorate ion?

Accepted Answer

ClO$$_3^-$$

Question 5

A molecule of H$$_2O is an $$example of which type of bond?

Accepted Answer

Polar covalent

Question 6

Which of the following best explains why NaCl forms an ionic bond?

Accepted Answer

The electronegativity difference ($$\Delta EN) $$between Na and Cl is greater than 2.0.

Question 7

What is the correct electron configuration for Mg$$^{2+}$$?

Accepted Answer

$$[Ne]$$

Question 8

Which of the following ions has the same electron configuration as Ne?

Accepted Answer

O$$^{2-}$$

Question 9

Which of the following best describes lattice energy in ionic compounds?

Accepted Answer

The energy released when gaseous ions combine to form an ionic solid.

Question 10

Which of the following is the correct formula for ammonium sulfate?

Accepted Answer

(NH$$_4$$)$$_2SO$_4$$

Question 11

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity increases across a period and decreases down a group.

Question 12

Which of the following compounds is named correctly?

Accepted Answer

Ca(NO$$_3$$)$$_2$$: calcium nitrate

Question 13

A sample contains 100 g of H$$_2O. $$How many molecules of water are present?

Accepted Answer

$$3 	imes 10$$^{24}$$ molecules

Question 14

Which of the following best describes the difference between a covalent and an ionic bond?

Accepted Answer

Covalent bonds involve sharing electrons, while ionic bonds involve transfer of electrons.

Question 15

Which of the following is the correct name for K$$_2Cr$_2O$_7$$?

Accepted Answer

Potassium dichromate

Question 16

Which of the following ions is isoelectronic with Ar?

Accepted Answer

Cl$$^-$$

Question 17

Which of the following best describes the trend in ionization energy across a period?

Accepted Answer

Ionization energy increases across a period due to increasing nuclear charge.

Question 18

Which of the following is the correct formula for hydrogen phosphate?

Accepted Answer

HPO$$_4$$^{2-}$$

Question 19

Which of the following best explains why O$$_2 is a $$nonpolar molecule?

Accepted Answer

Both atoms have the same electronegativity, so electrons are shared equally.

Question 20

Which of the following is the correct name for the compound (NH$$_4$$)$$_2CO$_3$$?

Accepted Answer

Ammonium carbonate

Polyatomic Ions, Covalent and Ionic Compounds, and Electronegativity: Core Concepts in General Chemistry

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