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ZIMSEC A Level · N2016

Chemistry Paper 2 November 2016

Questions
18
Total marks
28
Time allowed
75 min

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Questions
18
Pass mark
11
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Answer every question in the printed order, get marked at the end, then see the answers.

The questions

Question 101

[1 marks]atomic structure / isotopes
The element R has atomic number 31. Its electronic configuration is
  1. A1s22s22p63s23p64s23d91s^22s^22p^63s^23p^64s^23d^9
  2. B1s22s22p63s23p63d104s24p11s^22s^22p^63s^23p^63d^{10}4s^24p^1
  3. C1s22s22p63s23p63d94s24p21s^22s^22p^63s^23p^63d^94s^24p^2
  4. D1s22s22p63s23p63d104s11s^22s^22p^63s^23p^63d^{10}4s^1

Question 102

[1 marks]atomic structure / isotopes
Element R exists as two components of mass numbers 69 and 71. These components are called
  1. Aions
  2. Ballotropes
  3. Cisotopes
  4. Disomers

Question 103

[1 marks]atomic structure / isotopes
Element R consists of atoms of mass number 69 and 71 and has ArA_r = 69.8. The percentage of the isotope of mass number 69 is
  1. A30 %
  2. B40 %
  3. C60 %
  4. D70 %

Question 104

[1 marks]atomic structure / isotopes
Element R consists of atoms of mass number 69 and 71. Given that the isotope of mass number 69 makes up 60 % of R, the percentage of the isotope of mass number 71 is

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Question 201

[1 marks]bonding / acids and buffers
Trimethylamine, N(CH3)3N(CH_3)_3, reacts with boron trifluoride to form a solid salt. The bond formed between the two molecules is
  1. Aionic
  2. Bhydrogen
  3. Ca dative covalent bond
  4. Da non-polar covalent bond

Question 202

[1 marks]bonding / acids and buffers
0.1 mol dm−30.1\ mol\,dm^{-3} hydrochloric acid has a pH of 1, while 0.1 mol dm−30.1\ mol\,dm^{-3} ethanoic acid has a pH of about 3. This is because ethanoic acid
  1. Ais only partially dissociated in solution
  2. Bis more concentrated than the hydrochloric acid
  3. Ccontains fewer hydrogen atoms per molecule
  4. Dreacts with water to form a buffer

Question 203

[1 marks]bonding / acids and buffers
A buffer of ammonia and ammonium chloride has a pH of 10.0. Given that Ka(NH4+)=6×10−10 mol dm−3K_a(NH_4^+) = 6 \times 10^{-10}\ mol\,dm^{-3}, the ratio [NH4+]/[NH3][NH_4^+]/[NH_3] is
  1. A0.167
  2. B1.00
  3. C6.00
  4. D10.0

Question 204

[2 marks]bonding / acids and buffers
Write an equation for the dissociation of ethanoic acid, CH3COOH, in water.

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Question 205

[2 marks]bonding / acids and buffers
A buffer solution is best defined as a solution that
  1. Ahas a pH of exactly 7 at all times, no matter what is added to it.
  2. Breacts completely with any acid or base added, fully neutralising it.
  3. Ccontains only a strong acid dissolved together with its conjugate base.
  4. Dresists changes in pH when small amounts of acid or base are added to it.

Question 206

[1 marks]bonding / acids and buffers
In the dative covalent bond formed between N(CH3)3N(CH_3)_3 and BF3BF_3, the atom that donates the lone pair is

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Question 301

[1 marks]Group IV / halogens
A solution of chlorine in water still smells of chlorine because
  1. Achloric(I) acid has a chlorine smell
  2. Bthe equilibrium lies to the left, so dissolved Cl2Cl_2 remains
  3. Chydrochloric acid decomposes to give chlorine
  4. Dchlorine is insoluble in water

Question 302

[1 marks]Group IV / halogens
Adding aqueous alkali to chlorine water removes the smell of chlorine because the alkali
  1. Aneutralises the acids formed, shifting the equilibrium to the right
  2. Bforms a precipitate with the chlorine
  3. Creduces the chlorine to chloride ions only
  4. Dlowers the solubility of chlorine

Question 303

[1 marks]Group IV / halogens
Down Group IV the +4+4 oxidation state
  1. Abecomes more stable, because the atoms get larger
  2. Bremains equally stable throughout the group
  3. Cbecomes more stable, because the elements become more metallic
  4. Dbecomes less stable relative to +2+2, because of the inert pair effect

Question 304

[3 marks]Group IV / halogens
Diamond has a much higher melting point than lead. This is best explained by the fact that
  1. Adiamond has a giant covalent (macromolecular) structure with strong covalent bonds throughout, while lead has weaker metallic bonding.
  2. Bdiamond atoms are held together only by van der Waals forces, which require more energy to overcome than lead's metallic bonds.
  3. Clead has a much larger atomic radius than carbon, which lowers the energy needed to melt it.
  4. Dlead has an ionic lattice held together by strong electrostatic forces, while diamond has only weak intermolecular forces between molecules.

Question 305

[1 marks]Group IV / halogens
The stable oxide formed when carbon (diamond) is fully oxidised is

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Question 306

[1 marks]Group IV / halogens
Down Group (IV), the oxides of carbon and silicon are acidic, while the oxide of lead is

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Question 307

[2 marks]Group IV / halogens
In the equilibrium Cl2+H2O⇌HCl+HOClCl_2 + H_2O \rightleftharpoons HCl + HOCl, the product responsible for the bleaching and antiseptic action of chlorine water is

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Question 308

[1 marks]Group IV / halogens
Because of the inert pair effect, the more stable oxide of lead is

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