Which
of
the
following
is
a
property
of
water?
A.
When
water
freezes
to
ice
it
expands
B.
When
water
freezes
to
ice
it
contracts
C.
Water
is
a
nonpolar
molecule
D.
Most
water
on
Earth
is
freshwater
(A)
The
correct
answer
is
(A).
When
water
freezes,
its
molecules
arrange
in
crystalline
form
because
it
is
a
polar
molecule
(has
a
positive
and
negative
end).
The
arrangement
of
molecules
in
ice
takes
up
more
space
than
it
does
in
liquid
form.
This
property
explains
why
potholes
in
roads
are
caused
by
freezing
and
thawing
(melting)
of
water
in
the
cracks
of
roads
in
winter,
and
why
the
ice
cubes
in
an
ice
cube
tray
in
a
freezer
are
larger
than
the
liquid
water
that
was
originally
poured
into
the
tray.
Option
(B)
is
incorrect
because
water
expands
when
it
freezes.
Option
(C)
is
incorrect
because
water
is
a
polar
molecule.
Option
(D)
is
incorrect
because
most
water
on
Earth
is
saltwater,
with
only
2.5
percent
freshwater.
Topic:
904-016
Cycles
in
Earth
Systems
