Question 1

Which of the following best describes the bond in H$$_2O $$based on the electronegativity values given (H: 2.2, O: 3.5)?

Accepted Answer

Polar covalent, because the electronegativity difference is significant but not enough for full electron transfer.

Question 2

What is the correct Lewis structure for formaldehyde (CH$$_2O$$)?

Accepted Answer

A central carbon atom with two single bonds to hydrogen and a double bond to oxygen, with two lone pairs on oxygen.

Question 3

Which of the following is the correct formula for calculating formal charge (FC) on an atom in a Lewis structure?

Accepted Answer

$$\mathrm{FC = Group\ number - (number\ of\ associated\ electrons)}$$

Question 4

Given the Lewis structure for OH$$^-$$, what is the formal charge on the oxygen atom?

Accepted Answer

$$-1$$

Question 5

Which of the following best explains why water (H$$_2O) $$has a net dipole moment?

Accepted Answer

The molecule is bent, so the dipoles add up to create a net dipole.

Question 6

Which of the following is the correct name for N$$_2O$_3$$?

Accepted Answer

Dinitrogen trioxide

Question 7

What is the total number of valence electrons in the Lewis structure for BF$$_4^-$$?

Accepted Answer

$$32$$

Question 8

Which of the following statements about formal charge and real charge distribution is correct?

Accepted Answer

Formal charge is a bookkeeping tool, while real charge distribution depends on electronegativity and structure.

Question 9

Which of the following is the correct order for drawing a Lewis structure for a covalent compound?

Accepted Answer

Count valence electrons, put least electronegative atom in center, connect perimeter atoms with single bonds, add lone pairs to perimeter atoms, add leftover electrons to central atom, form multiple bonds if needed.

Question 10

Which of the following compounds is named correctly according to the rules for binary covalent compounds?

Accepted Answer

CO$$_2 as $$carbon dioxide

Question 11

What is the formal charge on nitrogen in NH$$_4^+$$?

Accepted Answer

$$+1$$

Question 12

Which of the following best describes the bond in NaH (sodium hydride)?

Accepted Answer

Ionic, with H$$^-$$ and Na$$^+$$ ions

Question 13

If you are naming BrCl, which rule determines the order of the elements in the name?

Accepted Answer

The element with the higher period (row) number is named first.

Question 14

Which of the following is the correct Lewis structure for HCN (hydrogen cyanide)?

Accepted Answer

H single bonded to C, which is triple bonded to N, with a lone pair on N.

Question 15

Which of the following best explains why the formal charge on boron in BF$$_4^- is$$ $$-1$$?

Accepted Answer

Boron has one more electron than its group number due to the extra electron from the negative charge.

Question 16

Which of the following is the correct calculation for the total charge on BF$$_4^-$$ using real charge distribution?

Accepted Answer

$$4 	imes (-0.55) + 1.20 = -1$$

Question 17

Which of the following best describes the difference between formal charge and real charge distribution?

Accepted Answer

Formal charge is based on electron counting, while real charge distribution depends on electronegativity and molecular structure.

Question 18

Which of the following is the correct name for CO?

Accepted Answer

Carbon monoxide

Question 19

Which of the following steps is necessary if the central atom in a Lewis structure does not have an octet after all electrons are placed?

Accepted Answer

Convert a lone pair on a perimeter atom to a multiple bond with the central atom.

Polar Covalent Bonds, Naming Binary Covalent Compounds, Lewis Structures, and Formal Charge

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