The answer is the choice A
D has a total of four significant figures.
Answer:
The answer to your question is 50 moles of O₂
Explanation:
Balanced Chemical reactions
1.- N₂(g) + 3H₂ (g) ⇒ 2NH₃ (g)
2.- 4NH₃ (g) + 5O₂(g) ⇒ 4NO (g) + 6H₂O (l)
moles of N₂(g) = 20 moles
moles of O₂(g) = ?
Process
1.- Calculate the moles of NH₃
1 mol of N₂ ------------- 2 moles of NH₃
20 moles of N₂ --------- x
x = (20 x 2) / 1
x = 40 moles of NH₃
2.- Calculate the moles of O₂
4 moles of NH₃ -------------- 5 O₂
40 moles of NH₃ ------------ x
x = (40 x 5) / 4
x = 200 / 4
x = 50 moles of O₂
Given parameters:
Mass of sucrose = 5g
Density of sucrose = 1.12g/mL
Percentage of sucrose per liter of cane juice = 12%
Unknown:
Volume of cane juice needed = ?
We need to establish the volume - density relationship. Density is the mass of a substance per unit volume.
Mathematically;
Density = 
Now solve for the volume of sucrose;
1.12g/mL = 
Volume = 
= 4.46mL = 4.46 x 10⁻³L since 1000mL = 1L
Since 12% of 1 liter of cane juice is sucrose;
12% of x liter of cane juice = 4.46 x 10⁻³L
Volume of cane juice = 4.46 x 10⁻³ x 
= 0.037L
Volume of cane juice is 0.037L
Answer:
The cell reaction reaches equilibrium quickly and the cell emf becomes zero.
Explanation:
The purpose of a salt bridge is not to move electrons from the electrolyte, its main function is to maintain charge balance because the electrons are moving from one-half cell to the other.
A solution of a salt that dissociates easily is normally used. Water is ineffective at functioning as a salt bridge. Hence the effect stated in the answer.
