Question 1

Which of the following statements best explains why carbon is the central element in organic chemistry?

Accepted Answer

Carbon can form up to four covalent bonds, allowing for a variety of stable structures.

Question 2

Which of the following is the correct electronic configuration for a nitrogen atom?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^3$$

Question 3

Which of the following best describes the difference between a sigma ($$\sigma) $$bond and a pi ($$\pi) $$bond?

Accepted Answer

A $$\sigma$$ bond results from head-on overlap of orbitals, while a $$\pi$$ bond results from side-by-side overlap of p orbitals.

Question 4

Which of the following molecules contains a polar covalent bond?

Accepted Answer

HCl

Question 5

What is the formal charge on the oxygen atom in the hydronium ion ($$H_3O^+$$)?

Accepted Answer

+1

Question 6

Which of the following is the major resonance contributor for the formate ion ($$HCO_2$$^-$$)?

Accepted Answer

The structure with the negative charge on the oxygen atom.

Question 7

Which hybridization and geometry best describe the central carbon atom in methane ($$CH_4$$)?

Accepted Answer

sp$$^3$$ hybridization, tetrahedral geometry

Question 8

Which of the following statements about resonance is correct?

Accepted Answer

Resonance forms differ only in the arrangement of electrons, not the arrangement of atoms.

Question 9

Which of the following best explains why rotation around a double bond is restricted?

Accepted Answer

The presence of a $$\pi$$ bond above and below the plane of the atoms prevents rotation.

Question 10

Which of the following is a constitutional isomer of butanol ($$C_4H_{10}O$$)?

Accepted Answer

Diethyl ether ($$CH_3CH_2OCH_2CH_3)$$

Question 11

What is the bond angle expected in ammonia ($$NH_3) $$due to its electron pair geometry?

Accepted Answer

Slightly less than $$109.5^\circ$$

Question 12

Which of the following best describes the molecular shape of boron trifluoride ($$BF_3$$)?

Accepted Answer

Trigonal planar

Question 13

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity increases from left to right across a period.

Question 14

Which of the following best describes the bonding in ethylene ($$C_2H_4$$)?

Accepted Answer

Each carbon forms three $$sp^2$$ hybridized sigma bonds and one pi bond.

Question 15

Which of the following is true about the formal charge calculation for an atom in a molecule?

Accepted Answer

$$	ext{Formal charge} = [	ext{group number}] - [	ext{nonbonding electrons}] - \frac{1}{2}[	ext{shared electrons}]$$

Question 16

Which of the following best explains why the major resonance contributor for the cyanate ion ($$NCO^-) $$has the negative charge on the oxygen atom?

Accepted Answer

Oxygen is more electronegative than nitrogen or carbon.

Question 17

Which of the following is a correct condensed structural formula for acetone?

Accepted Answer

$$CH_3COCH_3$$

Question 18

Which of the following best describes the difference between constitutional isomers and stereoisomers?

Accepted Answer

Constitutional isomers differ in the connectivity of atoms, while stereoisomers differ only in the spatial arrangement of atoms.

Question 19

Which of the following statements about line-angle drawings is correct?

Accepted Answer

Each vertex or line ending represents a carbon atom, and hydrogens attached to carbon are not shown.

ORGO: Chapter 1

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