chemistry

6 in which molecule are all the outer-shell electrons involved in covalent bonding?
a cl, bch, c hcl d nh;

9 the formula of a compound containing element x is naz2x20s3.
the relative formula mass of the compound is 158.
what is the relative atomic mass of x?
a 32 b 59.5 cc 64 d 119

21 which oxides are basic?
1 calcium oxide
2 sodium oxide
3 iron(ii) oxide
a 1,2and3 b 1tand2only c 2and3only' d_= 3only

36 ethanol can be manufactured by fermentation or by the catalytic addition of steam to ethene.
which statements describe an advantage of manufacturing ethanol by fermentation?
1 the yield of ethanol is low.
2 the method uses a batch process.
3 the process takes place at a lower temperature.
4 the ethanol is made from a renewable source.
a iand2 b 1and3 c 2and4 d 3and4

3 which diagram represents one helium atom?
a b cc d
o key
@ = proton
o = neutron
° 7 © "9 68 o = electron
o

7 which row describes the properties of silicon(iv) oxide?
[ear [er
structure
a no high
b no low
cc yes high
d yes low

5 nitrogen forms a nitride ion with the formula n*.
which particle does not have the same electronic configuration as the nitride ion?
a al* b cr cc na* d oo

11 ethene gas, c2h,, is completely burned in excess oxygen to form carbon dioxide and water.
the equation for this exothermic reaction is shown.
coh, + 302 + 2co, + 2h,o0
the table shows the bond energies involved in the reaction.
bond energy
in kj/mol

c=c 614

c-h 413

o=o 495

c=o 799

o-h 467
what is the total energy change in this reaction?
a -954kj/mol
b -1010kj/mol
c -1313kj/mol
d -1369kj/mol

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