Which of these species contains the shortest carbon to oxygen bond length?

A.  ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{O}}^{-}$

B.  ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$

C.  ${\mathrm{CH}}_3{\mathrm{COO}}^{-}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

D

More than 60% of the candidates identified the compound with the shortest C to O bond as ethanoic acid, with the most common incorrect answer being the ethanoate ion.

In which of the following compounds does ionic bonding predominate?

A.  HCl

B.  NaF

C.  NH₄Br

D.  NaOH

B

A well answered question. 70% of the candidates selected NaF as the compound in which ionic bonding predominates. Several teachers expressed concern regarding the unusual wording of this question, but thankfully the candidates understood it in the right way.

Which metal has the strongest metallic bonding?

A.     Na

B.     Mg

C.     Al

D.     Ca

C

Which combination corresponds to a strong metallic bond?

B

The concept of charge and ionic radii size on the strength of the bond was answered well but had one of the lowest discriminatory indices on the paper.

Which combination causes the strength of metallic bonding to increase?

D

A straight-forward question about factors affecting the strength of metallic bonding answered correctly by 86 % of candidates. The distractors were almost equally chosen by the rest of the candidates.

What is the IUPAC name of NiCO₃?

A. nickel(II) carbonate

B. nickel carbonate

C. nickel(I) carbonate

D. nitrogen(I) carbonate

A

More than 81 % of candidates could correctly apply IUPAC nomenclature for an inorganic substance.

Which combination describes the bonding and structure in benzoic acid, C₆H₅COOH?

B

What is the order of increasing boiling point?

A. CH₃CH₂CH₂CH₃ < CH₃CH(OH)CH₃ < CH₃COCH₃ < CH₃CO₂H

B. CH₃CH₂CH₂CH₃ < CH₃COCH₃ < CH₃CH(OH)CH₃ < CH₃CO₂H

C. CH₃CO₂H < CH₃COCH₃ < CH₃CH(OH)CH₃ < CH₃CH₂CH₂CH₃

D. CH₃CH₂CH₂CH₃ < CH₃COCH₃ < CH₃CO₂H < CH₃CH(OH)CH₃

B

Ranking compounds in order of increasing boiling points proved challenging. There existed a number of misconceptions based on the incorrect answers chosen. Wrong answers were evenly distributed.

How does a lithium atom form the most stable ion?

A. The atom gains a proton to form a positive ion.

B. The atom loses a proton to form a negative ion.

C. The atom loses an electron to form a positive ion.

D. The atom gains an electron to form a negative ion.

C

One of the most straight-forward questions on the paper about how lithium forms its most stable ion.

Which atom has an expanded octet?

A.  C in CO₂

B.  S in SCl₄

C.  O in H₂O₂

D.  P in PCl₃

B

What are the electron domain and molecular geometries of the XeF₄ molecule?

C

Higher scoring candidates had greater success in correctly identifying electron domain and molecular geometry of the XeF₄ molecule.

How many electrons form the carbon–oxygen bond in methanal, HCHO?

A. 2

B. 4

C. 8

D. 12

B