The mole fraction of a product is the number of moles of the product divided by the total number of moles of the solution.
Here moles of methanol = 6.0 moles
Moles of solution = 6.0 moles of methanol + 3.0 moles of water = 9.0 moles of solution
Mole fraction of methanol = 6.0 / 9.0 = 0.67
Answer: 0.67
The answer is A. The pH decreases
Answer:

Explanation:
(a) Balanced equation
2Zn + O₂ ⟶ 2ZnO
(b). Calculation
You want to convert moles of ZnO to moles of Zn
The molar ratio is 2 mol Zn:2 mol ZnO

Density = mass / volume so
Density = 156 / 20.0
Density = 7.8 g/mL