%100 VERIFIED CHEMISTRY OBJ AND ESSAY ANSWERS

• Item 1 +++++++++++++++++++++++++++++++ Tuesday, 20th September, 2016 Chemistry (obj and essay) 9.30am +++++++++++++++++++++++++++++++

  1a the raw materials for the manufacture of synthetic polymeters are readilyand cheaply available from reftining of crude oil

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  1d)I)The transition elements are those elements having a partially filled d or f subshell in any common oxidation

  1d)ii)trasiction element have variable oxidation states because they do not have incomplete filled D-orbitals

  1d)iii)-for conducting electricity -for making malleable instruments

  1cii)

  No of mole=mass/molar mass =1.11/40+(35.5x2) =1.11/111 =0.01moles/dmcube

  20.0g dissolves 0.001moles Then 1000g dissolves 1000x0.01/20 Solubility=0.05mol/dmcube ====================

  3ai) Crystallisation is a separation technique that is used to separate. a solid that has dissolved in a liquid and made a solution. The solution is warmed in an open container, allowing the solvent to evaporate, leaving a saturated solution.

  3aii) Evaporation is the process of a substance in a liquid state changing to a gaseous state due to an increase in temperature and/or pressure.

  3aiii) Filtration is any of various mechanical, physical or biological operations that separate solids from fluids (liquids or gases) by adding a medium through which only the fluid can pass.

  3bi) i)Their Melting and Boiling Points increases down the group

  ii)Their atomic Radius increases down the group

  iii)Their Ionization Energy: decreases down the group ===================

  4a)I)HARD WATER:They will not form latter readily with soap.it contains a number of dissolved salts.

  Ii)Temporary hardness:Ca(OH)2 Permanent hardness:NaS03

  Iii)By using chemicals like caustiic soda. -By using permutot OR zeolite

  4b)I)-coagulation/flocculation -sedimentation -filtration -chlorination/disinfection

  4b)ii)-potash alum -iodine -fluorine

  4c)Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent.

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• Item 2