I believe that the answer is 12 because there is already 3 O molecules and since its in parentheses with 3 outside it that means that there are 3 of those CO molecules meaning that for every 1 CO there will be 3 O’s so 3, four times Is 12
Answer:

Explanation:
Given:
A solution contains one or more of the following ions such as Ag,
and 
Here the Lithium bromide is added to the solution and no precipitate forms
Solution:
Since with LiBr no precipitation takes place therefore Ag+ is absent
Here on adding
to it precipitation takes place.
Precipitate is as follows,

Thus,
is present
When
is added again precipitation takes place.
Therefore the reaction is as follows,

Therefore,
are present in the solution
Answer:
+5
Explanation:
The oxidation number of phosphorus can be obtained as follows:
H4P2O7 = 0
4(+1) + 2P + 7(—2) = 0
4 + 2P —14 = 0
Collect like terms
2P = 14 — 4
2P = 10
Divide both side by 2
P = 10/2
P = +5
The oxidation number of phosphorus is +5
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