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Date November 2017 Marks available 3 Reference code 17N.2.SL.TZ0.03
Level Standard level Paper Paper 2 Time zone TZ0 / no time zone
Command term Explain Question number 03 Adapted from N/A

Question

The figure represents a water molecule.

Draw a second water molecule to show how bonds can form between water molecules, including the name of the bond.

[2]
a.

Water has important solvent properties. Explain these properties using an example to illustrate your answer.

[3]
b.

Markscheme

a. similar water molecule drawn with oxygen on one molecule facing hydrogen on the other water molecule

b. one hydrogen bond drawn as a dotted/dashed line between the two water molecules and labelled

O and H do not have to be labelled but must be positioned correctly

eg :

Can get this mark even if atoms incorrect

a.

a. water molecule is polar

    OR

    water has «weak» positive and negative charges

c. water forms hydrogen bonds with polar substances

d. positive/hydrogen side/pole of water attracted to negative ions

    OR

    negative/oxygen side/pole attracted to positive ions

e. glucose/other example dissolves because it is polar

    OR

    sodium chloride/other example dissolves because ions are attracted to water

[Max 3 Marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Core » Topic 2: Molecular biology » 2.2 Water
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Core » Topic 2: Molecular biology
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