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4 marksForces of Attraction

CAPE Chemistry Unit 1 · May/June 2026 · Paper 2 · Question 1(f)

The boiling point of HCl is -85 °C whereas the boiling point of HF is 20 °C. With reference to the electronegativity of the halogen, explain the difference in the boiling point temperatures of HCl and HF.

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Other parts of this question

  1. 1(a)(i)Define mass number.[1 mark]
  2. 1(a)(ii)Define isotopes.[1 mark]
  3. 1(b)Element X has five naturally occurring isotopes as given in Table 1. Calculate the relative atomic mass of Element X.[3 marks]
  4. 1(c)(i)Define mole of a substance.[1 mark]
  5. 1(c)(ii)Define molar mass.[1 mark]
  6. 1(d)(i)Calculate the empirical formula of the product of the reaction between 10.0 g of lithium and excess oxygen that gave 21.5 g of lithium oxide.[4 marks]
  7. 1(d)(ii)State TWO postulates of Dalton's atomic theory that are highlighted by the reaction and associated calculations in (d)(i).[2 marks]
  8. 1(e)(i)Compare bonding in N2 and CaO in terms of electron interaction and polarity.[4 marks]
  9. 1(e)(ii)State the TWO types of intra-molecular bonds present in the NH4+ structure.[2 marks]
  10. 1(g)Calculate the volume of 4.10 g of Ar at STP. [1 mole of gas occupies 22.4 dm³ at STP.][2 marks]
  11. 1(h)Outline the experimental steps that can be used to determine the volume of a 0.1152 M solution of H2SO4 which would be required to neutralize 25.00 mL of a…[5 marks]

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