Transition Elements

7 free MDCAT Chemistry MCQs on Transition Elements (PM&DC syllabus), each with the answer, an explanation and the textbook line it comes from. Tap to check, no sign-up.

Tap an answer to check it · 7 questions

1. Question 1

   Transition elements show variable oxidation states because they can use:
   • AElectrons of inner f orbitals
   • BOnly the outer s electrons
   • COnly the outer p electrons
   • DInner d and outer s electrons
   Show answer and explanation

   Answer: D) Inner d and outer s electrons

   (n-1)d and ns electrons have comparable energy. Source: Chemistry 12 KPK (taleem360.com), p. 57.

2. Question 2

   Ions with completely filled or empty d orbitals, such as Zn2+ and Sc3+, are:
   • AColourless
   • BBlue
   • CGreen
   • DPurple
   Show answer and explanation

   Answer: A) Colourless

   Colour needs an incomplete d subshell in which electronic transitions can occur. Source: Chemistry 12 KPK (taleem360.com), p. 65.

3. Question 3

   V2O5 has replaced platinum as the catalyst in the contact process because platinum is:
   • AToo reactive with sulphur dioxide
   • BPoisoned by arsenic impurities
   • CUnable to adsorb oxygen
   • DMelted at the working temperature
   Show answer and explanation

   Answer: B) Poisoned by arsenic impurities

   Arsenic in the sulphur feedstock poisons Pt; V2O5 is not affected. Source: Chemistry 12 KPK (taleem360.com), p. 67.

4. Question 4

   Adding acid to a yellow potassium chromate solution:
   • AMakes it colourless
   • BGives green Cr3+ ions
   • CGives orange dichromate
   • DGives violet Cr2+ ions
   Show answer and explanation

   Answer: C) Gives orange dichromate

   2CrO4 2- + 2H+ <=> Cr2O7 2- + H2O shifts right; base shifts it back to yellow chromate. Source: Chemistry 12 KPK (taleem360.com), p. 70.

5. Question 5

   As the oxidation state of chromium increases, the acidic character of its oxides:
   • AFirst falls, then rises
   • BDecreases
   • CStays the same
   • DIncreases
   Show answer and explanation

   Answer: D) Increases

   CrO (+2) basic, Cr2O3 (+3) amphoteric, CrO3 (+6) acidic. Source: Chemistry 12 KPK (taleem360.com), p. 68.

6. Question 6

   Complexes with coordination number six have a shape that is:
   • ATetrahedral
   • BOctahedral
   • CSquare planar
   • DTrigonal bipyramidal
   Show answer and explanation

   Answer: B) Octahedral

   Coordination number four gives tetrahedral or square planar; five gives trigonal bipyramidal or square pyramidal. Source: Chemistry 12 KPK (taleem360.com), p. 62.

7. Question 7

   The IUPAC name of K3[Fe(CN)6] is:
   • APotassium hexacyanoferrate(II)
   • BPotassium hexacyanoiron(III)
   • CPotassium hexacyanoferrate(III)
   • DTripotassium cyanoiron(VI)
   Show answer and explanation

   Answer: C) Potassium hexacyanoferrate(III)

   Anionic complex, so iron becomes 'ferrate'; 3 K+ balance [Fe(CN)6]3-, so Fe is +3. Source: Chemistry 12 KPK (taleem360.com), p. 62.

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