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3 marksNon-Metals

CSEC Chemistry · January 2010 · Paper 2 · Question 6(b)

A mason advised a client to keep a freshly completed concrete floor moist while hardening to prevent cracks. The client was concerned this would stop the concrete from setting.

From your knowledge of the composition of cement and its use in making concrete, explain the reason for the mason's advice.

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Other parts of this question

  1. 6(a)(i)Describe the chemical composition of clay.[1 mark]
  2. 6(a)(ii)Suggest a possible source of 'glass' in fired clay.[1 mark]
  3. 6(a)(iii)Relate this use of clay to ONE of its properties.[2 marks]
  4. 6(c)(i)Name ONE plant fibre and ONE animal fibre used in making fabric, and state the chemical composition of plant fibres and animal fibres.[4 marks]
  5. 6(c)(ii)Suggest TWO chemical tests which may be used to distinguish an animal fibre from a plant fibre. Include the expected observations.[4 marks]

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