1.	How many σ and π bonds are present in a molecule of propyne, CH_3CCH?

| σ | π
A. | 5 | 3
B. | 6 | 2
C. | 7 | 1
D. | 8 | 0
(Total 1 mark)

2.	Which species does not contain delocalized electrons?
A.	CH_3CH_2O^–
B.	CH_3CO_2^–
C.	O_3
D.	NO_3^–
(Total 1 mark)

3.	Describe the delocalization of pi (π) electrons and explain how this can account for the structure and stability of the carbonate ion, CO_3^2–.
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(Total 3 marks)

4.	Explain the meaning of the term hybridization. State the type of hybridization shown by the carbon atoms in carbon dioxide, diamond, graphite and the carbonate ion.
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(Total 5 marks)

5.	How many sigma and pi bonds are there in propyne, CH_3CCH?
A.	2 sigma and 2 pi
B.	7 sigma and 1 pi
C.	6 sigma and 2 pi
D.	5 sigma and 3 pi
(Total 1 mark)

6.	Which species does not have delocalized electrons?
A.	NO_3^–
B.	NO_2^–
C.	O_3
D.	C_3H_6
(Total 1 mark)

7.	In which compound are all the carbon atoms sp^2 hybridized?

(Total 1 mark)

8.	Which statements about σ and π bonds are correct?
I.	σ bonds result from the axial overlap of orbitals.
II.	σ bonds only form from s orbitals.
III.	π bonds result from the sideways overlap of parallel p orbitals.
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

9.	In which substance does a carbon atom have sp^2 hybridization?
A.	2-methylbutan-1-ol
B.	Propyne, CH_3CCH
C.	C_60 fullerene
D.	Diamond
(Total 1 mark)

10.	The Lewis structure of XeF_2 contains two bonding pairs of electrons and three non-bonding pairs of electrons (lone pairs) around the central xenon atom. What is the shape of XeF_2 molecule?
A.	Bent
B.	Trigonal bipyramidal
C.	Square planar
D.	Linear
(Total 1 mark)

11.	How many sigma (σ) bonds are present in (CH_3)_2C=CClCH_2CH_3?
A.	1
B.	4
C.	16
D.	17
(Total 1 mark)

12.	Which molecule has an octahedral shape?
A.	SF_6
B.	PCl_5
C.	XeF_4
D.	BF_3
(Total 1 mark)

13.	Which species have delocalized electrons?
		
A.	I and II only
B.	I and III only
C.	II and III only
D.	I, II and III
(Total 1 mark)

14.	(a)	But-2-ene is a straight-chain alkene with formula C_4H_8. The molecule contains both σ and π bonds.

(i)	Explain the formation of the π bond.
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(2)
 
(ii)	For each of the carbon atoms, C(1) and C(2), identify the type of hybridization shown.
C(1): ..................................................................................................................
C(2): ..................................................................................................................
(1)

(b)	But-2-ene shows geometrical isomerism. Draw the structural formula and state the name of the other geometrical isomer.

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(2)
 
(c)	Identify the structural formula of an isomer of but-2-ene which does not decolorize bromine water, Br_2(aq).
(1)
(Total 6 marks)

15.	The reaction between N_2H_4(aq) and HCl(aq) can be represented by the following equation.
		N_2H_4(aq) + 2HCl(aq) → N_2H_6^2+(aq) + 2Cl^–(aq)
 
(i)	Identify the type of reaction that occurs.
(1)
 
(ii)	Predict the value of the H–N–H bond angle in N_2H_6^2+.
(1)
 
(iii)	Suggest the type of hybridization shown by the nitrogen atoms in N_2H_6^2+.
(1)
(Total 3 marks)

16.	Identify the hybridization of carbon atoms in this molecule

| 1 | 2 | 3 | 4
A. | sp^3 | sp^2 | sp^2 | sp^2
B. | sp^2 | sp^2 | sp^2 | sp
C. | sp^3 | sp | sp^2 | sp
D. | sp | sp^2 | sp | sp^2
(Total 1 mark)

17.	Which structure has delocalized π electrons?
A.	O_3
B.	CO
C.	HCN
D.	CO_2
(Total 1 mark)

18.	Draw the Lewis structures, state the shape and predict the bond angles for the following species.
(i)	PCl_3
(3)
 
(ii)	NH_2^–
(3)

(iii)	XeF_4
(3)
(Total 9 marks)

19.	How many bonding pairs and lone pairs of electrons surround the sulfur atom in the SF_4 molecule?

| Bonding pairs | Lone pairs
A. | 4 | 1
B. | 4 | 0
C. | 6 | 0
D. | 8 | 2
(Total 1 mark)

20.	Which of the following best describes the formation of π bonds?
A.	They are formed by the sideways overlap of parallel orbitals.
B.	They are formed by the axial overlap of orbitals.
C.	They are formed by the sideways overlap of an s and p orbital.
D.	They are formed by the axial overlap of either s or p orbitals.
(Total 1 mark)

21.	What is the hybridization of the carbon atom, and the number of σ and π bonds in the methanal molecule?

| Hybridization | σ bonds | π bonds
A. | sp^2 | 3 | 1
B. | sp^3 | 3 | 1
C. | sp^3 | 4 | 0
D. | sp^2 | 4 | 0
(Total 1 mark)

22.	Draw the Lewis structures, state the shapes and predict the bond angles for the following species.
(i)	SiF_6^2–
(3)
(ii)	NO_2^+
(3)
(Total 6 marks)

23.	What is the type of hybridization of the silicon and oxygen atoms in silicon dioxide?

| Silicon | Oxygen
A. | sp^3 | sp^3
B. | sp^3 | sp^2
C. | sp^2 | sp^3
D. | sp^2 | sp^2
(Total 1 mark)

24.	SF_2, SF_4 and SF_6 have different shapes. Draw their Lewis structures and use the VSEPR theory to predict the name of the shape of each molecule.

| SF_2 | SF_4 | SF_6
Lewis structure | | |
Name of shape | .................................... | .................................... | ....................................
(Total 6 marks)

25.	How many sigma (σ) and pi (π) bonds are present in the structure of HCN?
| σ | π
A. | 1 | 3
B. | 2 | 3
C. | 2 | 2
D. | 3 | 1
(Total 1 mark)

26.	How many lone pairs and bonding pairs of electrons surround xenon in the XeF_4 molecule?
| Lone pairs | Bonding pairs
A. | 4 | 8
B. | 0 | 8
C. | 0 | 4
D. | 2 | 4
(Total 1 mark)

27.	(i)	Apply the VSEPR theory to deduce the shape of , ICl_5 and SF_4. For each species, draw the Lewis (electron dot) structure, name the shape, and state the value of the bond angle(s).
(9)

(ii)	Discuss the bond angle(s) in SF_4.
(1)
 
(iii)	Explain the hybridization involved in the C_2H_4 molecule.
(4)
 
(iv)	State the hybridization involved in the  ion and comment on the nitrogen-oxygen bond distances.
(2)
 
(v)	Using Table 7 of the Data Booklet, predict and explain which of the bonds O-H, O-N or N-H would be most polar.
(2)
(Total 18 marks)

IB Questionbank Chemistry