Q: A sample contains $$5.0 \times 10$$^{18}$$ atoms of carbon. What is the mass of carbon in this sample? (Avogadro's number = 6.022$$ \times $$10^{23}$$, atomic mass of C = 12.01 g/mol)

$$\frac{5.0 \times 10$$^{18}$$}{6.022 \times 10$$^{23}$$} \times 12.01 = 1.0 \times 10$$^{-4}$$ g

Q: A molecule of hemoglobin contains four iron atoms. If the molar mass of hemoglobin is 64,500 g/mol, what is the mass percent of iron in hemoglobin? (Atomic mass of Fe = 55.85 g/mol)

$$\frac{4 \times 55.85}{64,500} \times 100 = 0.346\%$$

Question 1

Which of the following molecules is nonpolar, despite having polar bonds, due to its molecular geometry?

Accepted Answer

SF\_6

Question 2

What is the correct Lewis structure for carbon dioxide (CO\_2)?

Accepted Answer

O=C=O, with each O atom having two lone pairs

Question 3

Which of the following best describes the bond in NaCl?

Accepted Answer

Ionic bond

Question 4

Calculate the number of moles in 88.0 grams of CO\_2. (Molar mass of CO\_2 = 44.01 g/mol)

Accepted Answer

$$\frac{88.0}{44.01} = 2.00$$ moles

Question 5

Which of the following molecules has a bond angle closest to $$109.5^\circ$$?

Accepted Answer

CH\_4

Question 6

What is the empirical formula for a compound that is 63.16% carbon, 8.79% hydrogen, and 28.05% oxygen by mass?

Accepted Answer

C\_6H\_14O

Question 7

Which of the following statements about dipole moments is correct?

Accepted Answer

A molecule with polar bonds can be nonpolar if its geometry is symmetrical.

Question 8

How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in the molecule C\_2H\_2 (acetylene)?

Accepted Answer

3 $$\sigma$$, 2 $$\pi$$

Question 9

A sample contains $$5.0 	imes 10$$^{18}$$ atoms of carbon. What is the mass of carbon in this sample? (Avogadro's number = 6.022$$ 	imes $$10^{23}$$, atomic mass of C = 12.01 g/mol)

Accepted Answer

$$\frac{5.0 	imes 10$$^{18}$$}{6.022 	imes 10$$^{23}$$} 	imes 12.01 = 1.0 	imes 10$$^{-4}$$ g

Question 10

Which of the following best describes the hybridization of the central atom in SF\_4?

Accepted Answer

sp\^3d

Question 11

Which of the following molecules or ions is expected to have a square planar geometry?

Accepted Answer

XeF\_4

Question 12

What is the formal charge on the central atom in the Lewis structure of PO\_4\^{3-}?

Accepted Answer

$$5 - 0 - \frac{1}{2}(8) = +1$$

Question 13

Which of the following is the correct order of increasing electronegativity?

Accepted Answer

Na \u003c Mg \u003c Cl \u003c F

Question 14

A molecule of hemoglobin contains four iron atoms. If the molar mass of hemoglobin is 64,500 g/mol, what is the mass percent of iron in hemoglobin? (Atomic mass of Fe = 55.85 g/mol)

Accepted Answer

$$\frac{4 	imes 55.85}{64,500} 	imes 100 = 0.346\%$$

Question 15

Which of the following is the correct molecular formula for a compound with empirical formula CH\_2O and molar mass 180 g/mol?

Accepted Answer

C\_6H\_12O\_6

General Chemistry: Chemical Bonding, Molecular Structure, and Stoichiometry Study Notes

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