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Answer guide for O Level Chemistry (5070/2) – Paper 2 Theory June 2000
A1(a)
Sulphur dioxide
1
(b)
Magnesium oxide
1
(c )
iron
1
(d)
potassium hydroxide (A ( Allow magnesium oxide and lithium)
1
(e )
lithium
1
A2(a A2(a))
Same Same proto roton n or or ato atom mic numb umber / varie riety of sam samee ele eleme men nt an and diff differ eren entt mas masss num numbe berr / dif diffe fere rent nt numb number er of neut neutro rons ns (per (per atom atom))
1
6 protons, 6 electrons and 7 neutrons
1
Carbon dioxide + water —> —> glucose + oxygen
1
Any two from: Needs sunlight Needs chlorophyll Catalysed by enzymes
2
Any three from: Long chain hydrocarbons are broken down, in a reaction called cracking, at high temperature, in the presence of a catalyst
3
(b)
butene
1
(c )
C3H6
1
(d)
pentene / hexene
1
(e )
double bond shown as two pairs between carbon atoms
Answer guide for O Level Chemistry (5070/2) – Paper 2 Theory June 2000
B10(a)
ester
1
(b)(i)
contains a carbon-carbon double bond
1
(ii)
bromine
1
with saturated fat stays orange
1
with unsaturated fat changes from orange to colourless
1
oleic acid because it is unsaturated
1
stearic acid is saturated
1
boil / heat
1
with aqueous sodium hydroxide
1
(d)
polyester / terylene t erylene
1
B11(a) B11(a)(i) (i)
SiC has silico silicon n and and carbo carbon n combi combined ned,, diamo diamond nd only only has has carbo carbon n / SiC is a compound and diamond is an element / have different bond lengths 1
(iii) (c )
both have a tetrahedral carbon atom / coordination number of carbon is 4 / have the same bond angles / both are macromolecules 1 Any two from: High melting point Hard Non-conductor of electricity Insoluble in water
2
(c)(i)
quartz / sand
1
(ii)
3 moles of carbon makes 1 mole of SiC
1
36 g of carbon makes 40 g of SiC
1
So 18 tonnes of carbon makes 20 tonnes of SiC
1
(b)
(d)
Page 4 of 4
Two
from these: Water, carbon monoxide, carbon dioxide, silicon dioxide