Question 1

Which statement best describes the formation of an ionic bond between sodium (Na) and chlorine (Cl)?

Accepted Answer

Sodium atom loses an electron to become Na$^+$, and chlorine atom gains an electron to become Cl$^-$, resulting in electrostatic attraction between oppositely charged ions.

Question 2

Which factor increases the lattice energy of an ionic compound?

Accepted Answer

Increasing the charge of the ions.

Question 3

Why does NaCl have a high melting and boiling point?

Accepted Answer

Because it is composed of giant ionic lattices with strong electrostatic forces between ions.

Question 4

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have delocalized electrons in a 'sea of electrons' that are free to move throughout the lattice.

Question 5

According to band theory, why can't insulators conduct electricity?

Accepted Answer

Because there is a large energy gap between the valence band and the conduction band, preventing electrons from moving freely.

Question 6

Which molecule is an example of a coordinate (dative covalent) bond?

Accepted Answer

NH$_4^+$

Question 7

Which of the following is an exception to the octet rule due to having less than 8 electrons around the central atom?

Accepted Answer

BF$_3$

Question 8

How many bonding pairs and lone pairs are present in a water (H$_2$O) molecule?

Accepted Answer

2 bonding pairs and 2 lone pairs

Question 9

Which statement about resonance structures is correct?

Accepted Answer

Resonance structures differ only in the location of $	ext{π}$ electrons and lone pairs, not in the arrangement of atoms.

Question 10

Given the formal charge formula $	ext{Formal charge} = 	ext{No. of valence e}^- 	ext{ in free atom} - \frac{1}{2} 	ext{No. of bonding e}^- - 	ext{No. of lone pair e}^-$, which Lewis structure is most stable?

Accepted Answer

The structure with the smallest formal charges and negative charges on the most electronegative atoms.

Question 11

Which of the following molecules is non-polar despite having polar bonds?

Accepted Answer

CO$_2$

Question 12

What is the molecular geometry of methane (CH$_4$) according to VSEPR theory?

Accepted Answer

Tetrahedral

Question 13

Which type of intermolecular force is present between molecules of hydrogen chloride (HCl)?

Accepted Answer

Permanent dipole-permanent dipole interaction

Question 14

Why does water (H$_2$O) have a higher boiling point than methane (CH$_4$)?

Accepted Answer

Water molecules have stronger hydrogen bonds compared to the weak London forces in methane.

Question 15

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

Accepted Answer

A $\sigma$ bond is formed by head-on overlap of orbitals, while a $\pi$ bond is formed by sideways overlap.

Question 16

Which hybridization is present in the central atom of ammonia (NH$_3$)?

Accepted Answer

sp$^3$

Question 17

Which intermolecular force is the strongest?

Accepted Answer

Hydrogen bonding

Question 18

Which of the following compounds is most soluble in water?

Accepted Answer

Sodium chloride (NaCl)

Question 19

Which factor decreases the boiling point of branched alkanes compared to straight-chain alkanes?

Accepted Answer

Branched alkanes have less surface area for intermolecular forces, resulting in weaker London forces.

Question 20

Which statement correctly describes the effect of lone pairs on molecular geometry?

Accepted Answer

Lone pairs decrease the bond angle due to increased repulsion compared to bonding pairs.

Molecules and Molecular Structure: Chemical Bonding Study Notes

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