Dot-and-cross diagrams — Paper 1 · A Level Chemistry 9701

4 When barium metal burns in oxygen, the ionic compound barium peroxide, BaO2, is formed. Which dot-and-cross diagram represents the electronic structure of the peroxide anion in BaO2? key A B C D electron from first oxygen atom electron from second oxygen atom electron from barium atom

1 marks

Answer: D

This question in 9701/11 May/June 2008

33 Sodium hydrogensulfide, NaSH, is used to remove hair from animal hides. Which statements about the SH– ion are correct? 1 It contains 18 electrons. 2 Three lone pairs of electrons surround the sulfur atom. 3 Sulfur has an oxidation state of +2.

1 marks

Answer: B

This question in 9701/11 May/June 2010

2 Which diagram correctly shows the bonding in the ammonium ion, NH4 +? key A B N electron + + H H H electron H N H H N H H H C D + + H H H N H H N H H H

1 marks

Answer: C

This question in 9701/12 May/June 2011

1 In which species does the underlined atom have an incomplete outer shell? A BF3 B CH3 – C F2O D H3O+

1 marks

Answer: A

This question in 9701/11 May/June 2012

2 In which species does the underlined atom have an incomplete outer shell? A BF3 B CH3 – C F2O D H3O+

1 marks

Answer: A

This question in 9701/13 May/June 2012

13 Aluminium chloride catalyses certain reactions by forming carbocations with chloroalkanes as shown. RCl + Al Cl 3 → R+ + Al Cl 4 – Which property makes this reaction possible? A Al Cl 3 exists as the dimer Al 2Cl 6 in the vapour. B Al Cl 3 is a covalent molecule. C The aluminium atom in Al Cl 3 has an incomplete octet of electrons. D The chlorine atom in RCl has a vacant p orbital.

1 marks

Answer: C

This question in 9701/13 May/June 2012

3 Sodium borohydride, NaBH4, and boron trifluoride, BF3, are compounds of boron. What are the shapes around boron in the borohydride ion and in boron trifluoride? borohydride ion boron trifluoride A square planar pyramidal B square planar trigonal planar C tetrahedral pyramidal D tetrahedral trigonal planar

1 marks

Answer: D

This question in 9701/11 Oct/Nov 2012

12 In which pair do the molecules have the same shape as each other? A H2O and CO2 B H2O and SCl 2 C NH3 and BH3 D SCl 2 and BeCl 2

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2012

35 In the gas phase, aluminium chloride exists as the dimer, Al2Cl6. By using this information, which of the following are structural features of the Al2Cl6 molecule? 1 Each aluminium atom is surrounded by four chlorine atoms. 2 There are twelve non-bonded electron pairs in the molecule. 3 Each aluminium atom contributes electrons to four covalent bonds.

1 marks

Answer: D

This question in 9701/13 Oct/Nov 2012

9 Dicarbon monoxide, C2O, is found in dust clouds in space. Analysis of it shows that the sequence of atoms in this molecule is C – C – O. All bonds are double bonds and there are no unpaired electrons. How many lone pairs of electrons are present in a molecule of C2O? A 1 B 2 C 3 D 4

1 marks

Answer: C

This question in 9701/12 May/June 2013

2 Which compound has the greatest total number of lone pairs of electrons in the valence shells of all of its atoms? A CH3Cl B CO2 C N2H4 D NH4CN

1 marks

Answer: B

This question in 9701/13 May/June 2014

5 Dicarbon monoxide, C2O, is found in dust clouds in space. The structure of this molecule is C=C=O. The molecule contains no unpaired electrons. How many lone pairs of electrons are present in a molecule of C2O? A 1 B 2 C 3 D 4

1 marks

Answer: C

This question in 9701/11 May/June 2016

32 Which molecules and ions have a bond angle of 120°? 1 BF3 2 CH3 – 3 NH3

1 marks

Answer: D

This question in 9701/11 Oct/Nov 2018

5 In which species is there a lone pair of electrons? A CH3 B CH3 + C CH3 – D CH4

1 marks

Answer: C

This question in 9701/11 May/June 2019

32 A carbon monoxide molecule, CO, has three bonds between the carbon atom and the oxygen atom. Which features are present in one CO molecule? 1 two lone pairs of electrons 2 a co-ordinate (dative covalent) bond from oxygen to carbon 3 two π bonds

1 marks

Answer: A

This question in 9701/12 Oct/Nov 2019

8 A stable ion N5 + has been produced by research chemists. Which structure is most likely to show the electron arrangement of this ion? + A N N N N N + B N N N N N + C N N N N N + D N N N N N

1 marks

Answer: C

This question in 9701/12 Feb/March 2020

2 Which molecule contains six bonding electrons? A NCl 3 B H2S C C2H4 D SF6

1 marks

Answer: A

This question in 9701/13 May/June 2020

9 At 200 °C aluminium chloride is a gas with Mr = 267. What is the number of covalent bonds, dative covalent bonds and Ione pairs of electrons in one molecule of aluminium chloride at 200 °C? covalent dative Ione pairs bonds covalent bonds A 6 2 0 B 6 2 16 C 6 2 18 D 3 0 9

1 marks

Answer: B

This question in 9701/13 May/June 2020

34 Which molecules contain at least one unpaired electron? 1 NO 2 NO2 3 NH3

1 marks

Answer: B

This question in 9701/13 Oct/Nov 2021

6 Which molecule has an equal number of bonding electrons and lone-pair electrons? A BH3 B CO2 C F2O D SO2

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2022

13 VSEPR theory should be used in answering this question. The dot-and-cross diagram for an ozone, O3, molecule is shown. O O O What is the predicted bond angle in this molecule? A 107 B 109.5 C 117 D 120

1 marks

Answer: C

This question in 9701/12 Oct/Nov 2022

6 Which molecule has an equal number of bonding electrons and lone-pair electrons? A BH3 B CO2 C F2O D SO2

1 marks

Answer: B

This question in 9701/13 Oct/Nov 2022

20 HCN has been detected in interstellar gas. The molecules below have also been detected in interstellar gas. Which molecule contains the same total number of valence shell (outer shell) electrons as HCN? A HNO B NH3 C NO D PN

1 marks

Answer: D

This question in 9701/13 May/June 2023

6 Which row is correct? shape of H3O+ shape of SCl 2 A pyramidal non-linear B pyramidal linear C trigonal planar non-linear D trigonal planar linear When an evacuated tube of volume 400cm3 is filled with gas at 300K and 101kPa, the mass of

1 marks

Answer: A

This question in 9701/11 Oct/Nov 2023

7 Two compounds of boron are sodium borohydride, NaBH4, and boron trifluoride, BF3. What are the shapes of the borohydride ion and the boron trifluoride molecule? borohydride ion boron trifluoride A square planar pyramidal B square planar trigonal planar C tetrahedral pyramidal D tetrahedral trigonal planar In an experiment, 0.100mol of propan-1-ol is burnt completely in 12.0dm3 of oxygen, measured at

1 marks

Answer: D

This question in 9701/12 Oct/Nov 2023

21 Which dot-and-cross diagrams represent molecules that can react with unburned hydrocarbons to form peroxyacetyl nitrate, PAN, a component of photochemical smog? 1 2 3 4 A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

1 marks

Answer: D

This question in 9701/13 May/June 2025

17 The table shows the numbers of bond pairs and lone pairs in four different species. Which row is correct? total number total number species of bond pairs of lone pairs A nitrogen molecule 3 1 B ammonia molecule 4 1 C ammonium ion 4 0 D hydroxide ion 1 4

1 marks

Answer: C

This question in 9701/14 May/June 2025

6 NH3 and HCN react together to form NH4CN, an ionic compound. Which row states the number of coordinate bonds and the number of  bonds in one formula unit of NH4CN? number of coordinate bonds number of  bonds A 0 2 B 1 2 C 0 3 D 1 3

1 marks

Answer: B

This question in 9701/11 Oct/Nov 2025