13 The graph below shows the number of people who visited doctors because of influenza-like illnesses over a two-year period.
2007-2008
2008-2009
Week of the year
What can
you
conclude from this graph?
F Influenza-like illnesses follow a steady pattern throughout the year.
G Scientists can predict that the number of influenza-like illnesses will decrease
for 2009-2010
H The severity of influenza-like symptoms decreased in 2008-2009.
I The number of people who developed influenza-like illnesses did not peak at
the same time in 2008-2009 as it did in 2007-2008.

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흠heum.

룰이 되었다 아직 되지 않는다.

pure substance: iron,copper

impure substance: water,charcoal

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o