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2 marksGroup II Elements

CAPE Chemistry Unit 1 · 2007 · Paper 2 · Question 3(d)(iii)

A student heated two calcium salts, A and B, and the following results were obtained. Compound A decomposed to give a gas which formed a white precipitate on being bubbled into an aqueous solution of calcium hydroxide. Compound B decomposed to give two gases. One gas was brown in colour and turned moist blue litmus paper red and the other gas rekindled a glowing splint.

Deduce the molecular formulae of the two calcium salts. Compound A: Compound B:

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Other parts of this question

  1. 3(a)(i)Describe the reaction of barium metal with water. Include a balanced equation.[4 marks]
  2. 3(a)(ii)Explain why the use of barium sulphate is acceptable in the X-ray analysis even though Ba²⁺ ions are toxic.[2 marks]
  3. 3(b)(i)Predict EACH of the following: Thermal stability of RaCO₃ relative to the other Group II carbonates[2 marks]
  4. 3(b)(ii)Predict EACH of the following: Ease of reaction between radium and oxygen[2 marks]
  5. 3(c)Magnesium oxide is used in the walls of industrial furnaces. Suggest an explanation for this usage.[2 marks]
  6. 3(d)(i)Identify the gas evolved on heating Compound A.[1 mark]
  7. 3(d)(ii)Identify the TWO gases evolved on heating Compound B.[2 marks]

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