02 Chemical Bonding, Set B To print: Ctrl + P, paper A4, margins Default.
Learners' AlleyDesigned by Khow Willard
02
Chemical Bonding
Set BExam practice
Name
Time 1 hour 15 minutes
Total 44 marks
A Data Booklet may be used.
A
Multiple choice
4 marks
1
CommonThe Valence Shell Electron Pair Repulsion theory (VSEPR) is used to predict the bond angles of molecules. Which bond angle is correctly predicted by VSEPR?
number of bonded electron pairs around central atom
number of lone pairs around central atom
bond angle
A
2
1
105°
B
2
2
118°
C
3
1
107°
D
3
2
90°
A
B
C
D
Answer [1]
Source: 2024 HCI J2 Prelim P1 Q3
2
Which bonding type does not correspond to its description of physical properties?
bonding type
physical properties
A
giant covalent
high melting point, conducts electricity when in solution but not when solid
B
simple covalent
low melting point, does not conduct electricity in any state
C
metallic
variety of melting points, conducts electricity when solid and when molten
D
ionic
high melting point, conducts electricity when molten but not when solid
A
B
C
D
Answer [1]
Source: A Level 2013 P1 Q5, via EJC 2022 JC1 Chemical Bonding Tutorial, A11
3
Which of the following statements describes a phenomenon which can be explained by intermolecular hydrogen bonding?
AThe melting points of the Group 1 hydroxides increase with increasing relative molecular mass (Mr).
BThe boiling points of the alkanes increase with increasing relative molecular mass.
CCH3OCH3 (Mr = 46) has a higher boiling point than CH3CH2CH3 (Mr = 44).
DIce has a lower density than water at 0 °C.
Answer [1]
Source: A Level 1990 P1 Q4 (modified), via EJC 2022 JC1 Chemical Bonding Tutorial, A10
4
Predict the most likely bond angle at each nitrogen atom in hydrazine, N2H4.
A107°
B109.5°
C118°
D120°
Answer [1]
Source: A Level 2009 P1 Q19 (modified), via EJC 2022 JC1 Chemical Bonding Tutorial, A5
B
Structured questions
40 marks
5
CommonSodium amide, NaNH2, is a salt that dissolves in liquid ammonia to form a solution containing NH2−.
(a)
With reference to the VSEPR theory, name the shapes of and state the bond angles for NH3 and NH2−. Explain your reasoning.
[3]
(b)
Explain why the melting point of NaNH2 (210 °C) is much higher than that of NH3 (−78 °C).
[2]
Source: 2023 HCI J2 Prelim P3 Q1(a)
6
The type of bonding present in a binary compound can be predicted from the electronegativities of the elements involved.
(a)
Describe and explain the variation in electronegativity across the third period of the Periodic Table.
[2]
(b)
State the type of bonding present in sodium fluoride (NaF), silicon tetrafluoride (SiF4) and the magnesium-aluminium alloy (Mg-Al).
Type of bonding in NaF:
Type of bonding in SiF4:
Type of bonding in Mg-Al:
[2]
Source: 2023 VJC J2 Prelim P2 Q2(a)(i) and (ii)
7
In the manufacture of tinted glass, a variety of carbonates including calcium carbonate were smelted together. State and explain, with reference to the VSEPR theory, the shape of the carbonate ion, CO32−.
[2]
Source: 2023 SAJC J2 Prelim P3 Q1(a)(ii)
8
CommonDimethyl ether has the formula CH3OCH3. Using your knowledge of VSEPR theory, state and explain the bond angle around the oxygen atom in CH3OCH3.
[2]
Source: 2025 NJC J2 Prelim P2 Q3(a)(ii)
9
When heated, butane reacts with chlorine to form 1-chlorobutane as one of the products. Explain why CH3CH2CH2CH3 has a lower boiling point than CH3CH2CH2CH2Cl.
[2]
Source: 2018 RI J1 Promo Section C Q1(a)
10
In each pair, which compound has the greater covalent character, and which would you expect to have the higher melting point? Explain.
Describe the structure and bonding in calcium with the aid of a labelled diagram.
[2]
Source: 2023 SAJC J2 Prelim P2 Q2(a)(iii)
13
Silane, SiH4, is a key raw material in the production of semiconductor-grade silicon.
(a)
CommonDraw the dot-and-cross diagram of silane. State the molecular shape about the central Si atom in silane.
[2]
(b)
Is the silane molecule polar or non-polar? Give a reason for your answer.
[1]
Source: 2023 YIJC J2 Prelim P2 Q1(b)
14
Silicon has a similar structure to diamond. However, the melting point of silicon, 1414 °C, is lower than that of diamond, 3550 °C. Explain this difference with reference to the structure and bonding of silicon and diamond.
[2]
Source: 2023 RI J2 Prelim P3 Q1(a)(i)
15
(a)
An oxygen molecule contains both a σ bond and a π bond. Describe how the orbitals overlap to form each bond.
[2]
(b)
State the number of σ bonds and π bonds in (i) ethane, C2H6, (ii) ethene, C2H4, (iii) ethyne, C2H2, and (iv) carbon dioxide, CO2.