Question 1

Which part of the atom contains most of its mass?

Accepted Answer

The nucleus (protons + neutrons)

Question 2

What is the correct shape of a p orbital?

Accepted Answer

Dumbbell-shaped

Question 3

How many electrons can the second shell of an atom hold?

Accepted Answer

$$8$$

Question 4

According to the Aufbau Principle, which orbital is filled first?

Accepted Answer

$$1s$$

Question 5

Which of the following best describes an ionic bond?

Accepted Answer

Electrostatic attraction between oppositely charged ions

Question 6

In the electron-dot structure of ammonia ($$NH_3$$), how many lone pairs are present on the nitrogen atom?

Accepted Answer

$$1$$

Question 7

Which molecule has four covalent bonds according to its line-bond structure?

Accepted Answer

Methane ($$CH_4)$$

Question 8

What is the bond length for the $$H-H$$ bond in a hydrogen molecule?

Accepted Answer

$$74\,pm$$

Question 9

How much energy is released when an $$H-H$$ bond forms?

Accepted Answer

$$104\,kcal/mol$$

Question 10

Which statement about sigma ($$\sigma) $$bonds is correct?

Accepted Answer

They are formed by the head-on overlap of two atomic orbitals along a line drawn between the nuclei

Question 11

Which orbital has a node separating two lobes with different algebraic signs?

Accepted Answer

$$2p$$ orbital

Question 12

What is the main difference between electron-dot and line-bond structures?

Accepted Answer

Electron-dot structures show all valence electrons, while line-bond structures represent shared electron pairs as lines

Question 13

Which of the following molecules contains a tetrahedral carbon atom?

Accepted Answer

Methane ($$CH_4)$$

Question 14

According to valence bond theory, what is required for a covalent bond to form?

Accepted Answer

A singly occupied orbital on one atom must overlap a singly occupied orbital on another atom

Question 15

Which of the following best explains why the $$H_2$$ molecule is more stable than two separate hydrogen atoms?

Accepted Answer

Energy is released when the $$H-H$$ bond forms, lowering the total energy

Question 16

Which of the following is true about the energy levels of the $$4s$$ orbital?

Accepted Answer

It falls between $$3p$$ and $$3d$$

Question 17

Which of the following molecules has three covalent bonds and one lone pair on the central atom?

Accepted Answer

Ammonia ($$NH_3)$$

Question 18

What is represented by a line between two atoms in a covalent bond?

Accepted Answer

A pair of shared electrons

Question 19

Which of the following is a correct statement about bond strength and bond length?

Accepted Answer

Bond strength is highest at the minimum energy point, which corresponds to the bond length

Question 20

Which of the following is NOT a correct representation of a $$2p$$ orbital?

Accepted Answer

It is spherical

Structure and Bonding: Foundations of Organic Chemistry

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