Answer:
The answer to your question is letter A. 2
Explanation:
Data
Octane = C₈H₁₈
Oxygen = O₂
Carbon dioxide = CO₂
Water = H₂O
Reaction
C₈H₁₈ + O₂ ⇒ CO₂ + H₂O
Reactants Elements Products
8 C 1
18 H 2
2 O 3
This reaction is unbalanced
C₈H₁₈ + 25/2O₂ ⇒ 8CO₂ + 9H₂O
Reactants Elements Products
8 C 8
18 H 18
25 O 25
Multiply the reaction by 2
2C₈H₁₈ + 25O₂ ⇒ 16CO₂ + 18H₂O
Reactants Elements Products
16 C 16
36 H 36
50 O 50
Now, the reaction is balanced
Answer: There are 
molecules present in 6.71 moles of 
.
Explanation:
Given: Moles of = 6.71 mol
According to the mole concept, 1 mole of every substance contains 
molecules.
Therefore, molecules present in 6.71 moles are calculated as follows.
Thus, we can conclude that there are molecules present in 6.71 moles of .
Reaction of Cu(NO₃)₂ with each salt is as follow,
1) with KNO₃;
Cu(NO₃)₂ + KNO₃ → Cu(NO₃)₂ + KNO₃
Both salt products are water soluble.
2) With CuSO₄;
Cu(NO₃)₂ + CuSO₄ → CuSO₄ + Cu(NO₃)₂
Again both Salt products are water soluble.
3) With K₂SO₄;
Cu(NO₃)₂ + K₂SO₄ → CuSO₄ + 2 KNO₃
Again both salt products are water soluble.
4) With K₂S;
Cu(NO₃)₂ + K₂S → CuS + 2 KNO₃
In this case CuS is water insoluble, hence precipitates out.
Result:
Option-4 is the correct answer.
The molar concentration will be greater than 0.01 M 
.
Since more of the compound was measured out than what was calculated, you can think of the solution as being 'stronger' than what it was calculated to be. Since a 'stronger' concentration results in a number that is higher, the molarity of this solution is going to be greater than 0.01 M.
