Question

2(a) A hydrocarbon having the formula C10H22 was cracked to produce C6H14 and another hydrocarbon P.
(i) Give the molecular formula of P.
(ii) Draw the structure of two isomers of P.
(iii) Give a reason why P could be polymerized. [4 marks]

Accepted Answer

(i) C10H22 → C6H14 + P. By balancing atoms, the molecular formula of P is C4H8 (but-1-ene or but-2-ene, an alkene).
(ii) Two isomers of P (C4H8):
  • But-1-ene: CH2=CH–CH2–CH3
  • But-2-ene: CH3–CH=CH–CH3
(iii) P can be polymerized because it is unsaturated — it contains a C=C double bond which can open up to link with other identical monomer units to form a polymer.

WAEC Chemistry 2019 Theory — Question 11

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