$$2.87 \times 10$$^{24}$$ atoms

Question 1

Which energy level (n) can hold a maximum of 18 electrons according to the formula $$2n^2$$?

Accepted Answer

$$n = 3$$

Question 2

How many valence electrons does an atom of oxygen (O) have?

Accepted Answer

6

Question 3

Which of the following elements will form a cation with a $$2+$$ charge by losing two valence electrons?

Accepted Answer

Magnesium (Mg)

Question 4

What is the electron configuration of a chloride ion ($$	ext{Cl}^-) $$after it gains one electron?

Accepted Answer

$$2-8-8$$

Question 5

Which polyatomic ion has the formula $$	ext{SO}_4$$^{2-}$$?

Accepted Answer

Sulfate

Question 6

What is the correct name for the compound $$	ext{MgCl}_2$$?

Accepted Answer

Magnesium chloride

Question 7

Which of the following compounds is covalent?

Accepted Answer

$$	ext{N}_2	ext{O}$$

Question 8

What is the molecular shape of methane ($$	ext{CH}_4) $$according to VSEPR theory?

Accepted Answer

Tetrahedral

Question 9

Which element is the most electronegative according to the periodic table?

Accepted Answer

Fluorine

Question 10

A molecule of $$	ext{CO}_2 is$$:

Accepted Answer

Nonpolar because its shape allows bond dipoles to cancel

Question 11

How many atoms are in $$4.78$$ moles of carbon?

Accepted Answer

$$2.87 	imes 10$$^{24}$$ atoms

Question 12

What is the molar mass of $$	ext{H}_2	ext{O}$$?

Accepted Answer

$$18.02\ 	ext{g/mol}$$

Question 13

Which of the following is the correct formula for calcium nitrate?

Accepted Answer

$$	ext{Ca(NO}_3)_2$$

Question 14

What is the formula mass of $$	ext{Na}_2	ext{CO}_3$$? (Na: 22.99, C: 12.01, O: 16.00)

Accepted Answer

$$105.99\ 	ext{amu}$$

Question 15

Which of the following best describes the bond in $$	ext{H}_2$$?

Accepted Answer

A nonpolar covalent bond

Question 16

What is the correct name for $$	ext{CO}_2$$?

Accepted Answer

Carbon dioxide

Question 17

Which compound contains a triple bond?

Accepted Answer

$$	ext{N}_2$$

Question 18

How many moles of Ag are in $$15.67 g of Ag$$? (Ag: $$107.9\ 	ext{g/mol})$$

Accepted Answer

$$0.145$$ moles

Question 19

Which of the following statements about ionic compounds is TRUE?

Accepted Answer

They are electrically neutral due to equal positive and negative charges

Question 20

Which rule explains why noble gases are chemically stable?

Accepted Answer

Octet rule

Chapter 3: Compounds

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