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</div><h2>HL Paper 1</h2><div class="question">
<p>[CoCl<sub>6</sub>]<sup>3–</sup> is orange while [Co(NH<sub>3</sub>)<sub>6</sub>]<sup>3+</sup> is yellow. Which statement is correct?</p>
<p>A. [CoCl<sub>6</sub>]<sup>3–</sup> absorbs orange light.</p>
<p>B. The oxidation state of cobalt is different in each complex.</p>
<p>C. The different colours are due to the different charges on the complex.</p>
<p>D. The different ligands cause different splitting in the 3d orbitals.</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>Cobalt forms the complex \({{\text{[Co(N}}{{\text{H}}_{\text{3}}}{{\text{)}}_{\text{5}}}{\text{Cl]}}^{2 + }}\). Which statements are correct for this complex?</p>
<p>I. The cobalt ion acts as a Lewis acid.</p>
<p>II. The cobalt ion has an oxidation number of +II.</p>
<p>III. There are 90° bond angles between the cobalt ion and the ligands.</p>
<p>A. I and II only</p>
<p>B. I and III only</p>
<p>C. II and III only</p>
<p>D. I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
<p>According to IUPAC, oxidation numbers are quoted in Roman numerals, oxidation states in Arabic. The nomenclature is clarified in the new syllabus, taught from September 2014.</p>
</div>
<br><hr><br><div class="question">
<p>Which ion is colourless?</p>
<p>A. \({{\text{[Sc(}}{{\text{H}}_{\text{2}}}{\text{O}}{{\text{)}}_{\text{6}}}{\text{]}}^{3 + }}\)</p>
<p>B. \({{\text{[Cr(}}{{\text{H}}_{\text{2}}}{\text{O}}{{\text{)}}_{\text{6}}}{\text{]}}^{3 + }}\)</p>
<p>C. \({{\text{[Fe(}}{{\text{H}}_{\text{2}}}{\text{O}}{{\text{)}}_{\text{6}}}{\text{]}}^{3 + }}\)</p>
<p>D. \({{\text{[Fe(CN}}{{\text{)}}_{\text{6}}}{\text{]}}^{3 - }}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>Which complex has the greatest d orbital splitting?</p>
<p><img src="images/Schermafbeelding_2018-08-07_om_09.28.41.png" alt="M18/4/CHEMI/HPM/ENG/TZ1/08"></p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>Part of the spectrochemical series is shown for transition metal complexes.</p>
<p style="text-align: center;">I<sup>−</sup>< Cl<sup>−</sup> < H<sub>2</sub>O < NH<sub>3</sub></p>
<p>Which statement can be correctly deduced from the series?</p>
<p>A. H<sub>2</sub>O increases the p–d separation more than Cl<sup>−</sup>.</p>
<p>B. H<sub>2</sub>O increases the d–d separation more than Cl<sup>−</sup>.</p>
<p>C. A complex with Cl<sup>−</sup> is more likely to be blue than that with NH<sub>3</sub>.</p>
<p>D. Complexes with water are always blue.</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>What is the charge on the iron(III) complex ion in [Fe(OH)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>]Br?</p>
<p>A. 0</p>
<p>B. 1+</p>
<p>C. 2+</p>
<p>D. 3+</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">What is the correct explanation for the colour of [Cu(H<sub><span class="s1">2</span></sub>O)<sub><span class="s1">6</span></sub>]<sup><span class="s1">2</span><span class="s2">+</span></sup>?</p>
<p class="p1">A. Light is absorbed when an electron moves to a d orbital of higher energy.</p>
<p class="p1">B. Light is released when an electron moves to a d orbital of higher energy.</p>
<p class="p1">C. Light is absorbed when electrons move from the ligands to the central metal ion.</p>
<p class="p1">D. Light is absorbed when electrons move between d and s orbitals.</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>The oxidation state of cobalt in the complex ion [Co(NH<sub>3</sub>)<sub>5</sub>Br]<em><sup>x</sup></em> is +3. Which of the following statements are correct?</p>
<p style="padding-left: 150px;">I. The overall charge, <em>x</em>, of the complex ion is 2+.<br>II. The complex ion is octahedral.<br>III. The cobalt(III) ion has a half-filled d-subshell.</p>
<p>A. I and II only</p>
<p>B. I and III only</p>
<p>C. II and III only</p>
<p>D. I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which complex is colourless in solution?</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>\({\text{[Fe(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_6}{\text{]C}}{{\text{l}}_2}\)</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>\({\text{[Ni(N}}{{\text{H}}_3}{{\text{)}}_6}{\text{]C}}{{\text{l}}_2}\)</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>\({\text{[Zn(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_6}{\text{](N}}{{\text{O}}_3}{{\text{)}}_2}\)</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>\({{\text{K}}_3}[{\text{Co(CN}}{{\text{)}}_6}]\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>Ammonia is a stronger ligand than water. Which is correct when concentrated aqueous ammonia solution is added to dilute aqueous copper(II) sulfate solution?</p>
<p>A. The d-orbitals in the copper ion split.</p>
<p>B. There is a smaller splitting of the d-orbitals.</p>
<p>C. Ammonia replaces water as a ligand.</p>
<p>D. The colour of the solution fades.</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which statements are correct about the complex \({\text{[Cu(N}}{{\text{H}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{C}}{{\text{l}}_{\text{2}}}{\text{]}}\)<span class="s1">?</span></p>
<p class="p2">I. <span class="Apple-converted-space"> </span>Oxidation state of copper is +<span class="s2">2.</span></p>
<p class="p1">II. <span class="Apple-converted-space"> </span>Ammonia is a ligand.</p>
<p class="p1">III. <span class="Apple-converted-space"> </span>Chloride ions act as Lewis acids.</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>I and II only</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>I and III only</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>II and III only</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p class="p1">A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
<p class="p1">Although several teachers had concerns about this one, overall it was a fair question with half the students answering it correctly. Surprisingly a quarter of the students incorrectly identified chloride ions acting as Lewis acids.</p>
</div>
<br><hr><br><div class="question">
<p>Which species have dative covalent bonding?</p>
<p>I. \({\text{[Fe(}}{{\text{H}}_{\text{2}}}{\text{O}}{{\text{)}}_{\text{6}}}{\text{]C}}{{\text{l}}_{\text{3}}}\)</p>
<p>II. \({\text{NH}}_4^ + \)</p>
<p>III. \({{\text{H}}_{\text{2}}}{\text{O}}\)</p>
<p>A. I and II only</p>
<p>B. I and III only</p>
<p>C. II and III only</p>
<p>D. I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which electron transitions are responsible for the colours of transition metal compounds?</p>
<p class="p1">A. Between d orbitals and s orbitals</p>
<p class="p1">B. Among the attached ligands</p>
<p class="p1">C. From the metal ion to the attached ligands</p>
<p class="p1">D. Between d orbitals</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which species cannot act as a ligand?</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>\({\text{NH}}_4^ + \)</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>\({{\text{H}}_{\text{2}}}{\text{O}}\)</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>\({\text{C}}{{\text{l}}^ - }\)</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>\({\text{O}}{{\text{H}}^ - }\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p class="p1">A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which solutions have a pH less than 7?</p>
<p class="p1">I. <span class="Apple-converted-space"> </span>\({\text{N}}{{\text{a}}_2}{\text{C}}{{\text{O}}_3}({\text{aq)}}\)</p>
<p class="p1">II. <span class="Apple-converted-space"> </span>\({\text{[Fe(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_6}{\text{]C}}{{\text{l}}_3}{\text{(aq)}}\)</p>
<p class="p1">III. <span class="Apple-converted-space"> </span>\({{\text{(N}}{{\text{H}}_4}{\text{)}}_2}{\text{S}}{{\text{O}}_4}{\text{(aq)}}\)</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>I and II only</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>I and III only</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>II and III only</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">What is the electron configuration of \({\text{S}}{{\text{n}}^{2 + }}\)?</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>\(1{{\text{s}}^2}2{{\text{s}}^2}2{{\text{p}}^6}3{{\text{s}}^2}3{{\text{p}}^6}4{{\text{s}}^2}3{{\text{d}}^{10}}4{{\text{p}}^6}5{{\text{s}}^2}4{{\text{d}}^{10}}5{{\text{p}}^2}\)</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>\(1{{\text{s}}^2}2{{\text{s}}^2}2{{\text{p}}^6}3{{\text{s}}^2}3{{\text{p}}^6}4{{\text{s}}^2}3{{\text{d}}^{10}}4{{\text{p}}^6}5{{\text{s}}^2}4{{\text{d}}^{10}}\)</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>\(1{{\text{s}}^2}2{{\text{s}}^2}2{{\text{p}}^6}3{{\text{s}}^2}3{{\text{p}}^6}4{{\text{s}}^2}3{{\text{d}}^{10}}4{{\text{p}}^6}4{{\text{d}}^{10}}5{{\text{p}}^2}\)</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>\(1{{\text{s}}^2}2{{\text{s}}^2}2{{\text{p}}^6}3{{\text{s}}^2}3{{\text{p}}^6}4{{\text{s}}^2}3{{\text{d}}^{10}}4{{\text{p}}^6}5{{\text{s}}^2}4{{\text{d}}^8}5{{\text{p}}^2}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<div class="page" title="Page 3">
<div class="layoutArea">
<div class="column">
<p>Which best explains why transition metal complexes are coloured?</p>
<p>A. As electrons return to lower energy levels, light of a certain colour is emitted, and the complementary colour is observed.</p>
<p>B. As electrons return to lower energy levels, light of a certain colour is emitted, so the complex appears to have the same colour.</p>
<p>C. As electrons are promoted to higher energy levels, light of a certain colour is absorbed, and the complementary colour is observed.</p>
<p>D. As electrons are promoted to higher energy levels, light of a certain colour is absorbed, so the complex appears to have the same colour.</p>
</div>
</div>
</div>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>What is the abbreviated electron configuration of the cobalt(II) ion, \({\text{C}}{{\text{o}}^{2 + }}\)?</p>
<p>A. \({\text{[Ar]3}}{{\text{d}}^{\text{7}}}\)</p>
<p>B. \({\text{[Ar]4}}{{\text{s}}^{\text{2}}}{\text{3}}{{\text{d}}^{\text{5}}}\)</p>
<p>C. \({\text{[Ar]4}}{{\text{s}}^{\text{2}}}{\text{3}}{{\text{d}}^{\text{7}}}\)</p>
<p>D. \({\text{[Ar]4}}{{\text{s}}^{\text{1}}}{\text{3}}{{\text{d}}^{\text{6}}}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Ligands can form dative covalent bonds with metal ions to form complex ions. Which of the following can act as a ligand?</p>
<p class="p1">I. <span class="Apple-converted-space"> </span>\({\text{C}}{{\text{l}}^ - }\)</p>
<p class="p1">II. <span class="Apple-converted-space"> </span>\({\text{N}}{{\text{H}}_{\text{3}}}\)</p>
<p class="p1">III. <span class="Apple-converted-space"> </span>\({{\text{H}}_{\text{2}}}{\text{O}}\)</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>I and II only</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>I and III only</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>II and III only</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which metal nitrate solution is coloured?</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>\({\text{Zn(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{(aq)}}\)</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>\({\text{Ni(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{(aq)}}\)</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>\({\text{Mg(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{(aq)}}\)</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>\({\text{Sc(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}{\text{(aq)}}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which process is responsible for the colour of a transition metal complex?</p>
<p class="p1">A. The absorption of light when electrons move between s orbitals and d orbitals</p>
<p class="p1">B. The emission of light when electrons move between s orbitals and d orbitals</p>
<p class="p1">C. The absorption of light when electrons move between different d orbitals</p>
<p class="p1">D. The emission of light when electrons move between different d orbitals</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">In which complexes does iron have an oxidation number of<span class="Apple-converted-space"> </span>\( + 3\)?</p>
<p class="p1">I. <span class="Apple-converted-space"> </span>\({{\text{[Fe(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_6}{\text{]}}^{3 + }}\)</p>
<p class="p1">II. <span class="Apple-converted-space"> </span>\({{\text{[Fe(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_5}{\text{(CN)]}}^{2 + }}\)</p>
<p class="p1">III. <span class="Apple-converted-space"> </span>\({{\text{[Fe(CN}}{{\text{)}}_6}{\text{]}}^{3 - }}\)</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>I and II only</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>I and III only</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>II and III only</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>Which compound is likely to be colourless?</p>
<p>A. \({\text{[Zn(}}{{\text{H}}_{\text{2}}}{\text{O}}{{\text{)}}_{\text{6}}}{\text{]C}}{{\text{l}}_{\text{2}}}\)</p>
<p>B. \({{\text{[N}}{{\text{H}}_{\text{4}}}{\text{]}}_{\text{2}}}{\text{[Fe(}}{{\text{H}}_{\text{2}}}{\text{O}}{{\text{)}}_{\text{6}}}{\text{][S}}{{\text{O}}_{\text{4}}}{{\text{]}}_{\text{2}}}\)</p>
<p>C. \({{\text{K}}_{\text{3}}}{\text{[Co(CN}}{{\text{)}}_{\text{6}}}{\text{]}}\)</p>
<p>D. \({\text{[Ni(N}}{{\text{H}}_{\text{3}}}{{\text{)}}_{\text{6}}}{\text{][B}}{{\text{F}}_{\text{4}}}{{\text{]}}_{\text{2}}}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br>