I would say the second option
Hope this helps *smiles*
Answer:
v = 658.82 km/h
Explanation:
The distance between New York and London is 
Time taken from New York to London is 8.5 hours
We need to find the average speed of the plane.
Total distance covered divided by the total time taken is equal to the average speed of an object. So,
So, the average speed of the plane is 658.82 km/h.
Answer:
poor hydrogen-ion donor
Explanation:
Acid dissociation constant constant chemistry is the equilibrium constant of the dissociation reaction of an acid, it is denoted by Ka. This equilibrium constant is a measure of the strength of an acid in a solution.
Note these as a rule of thumb:
When Ka is large, the dissociation of the acid is favored.
When Ka is small, the acid does not dissociate to a large extent.
Hence, a Ka of 4.3 x 10-7 shows a weak acid. A weak acid is a poor hydrogen ion donor because it does not dissociate to a large extent in solution.
Answer:
The percent by mass of copper in the mixture was 32%
Explanation:
The ammount of HNO₃ used is:
mol HNO₃ = volume * concentration
mol HNO₃ = 0.015 l * 15.8 mol/l
mol HNO₃ = 0.237 mol
According to the reaction, 4 mol HNO₃ will react with 1 mol Cu and produce 1 mol Cu²⁺. Since we have 0.237 mol HNO₃, the amount of Cu that could react would be (0.237 mol HNO₃ * 1 mol Cu / 4 mol HNO₃) 0.06 mol. This reaction would produce 0.060 mol Cu²⁺, however, only 0.010 mol Cu²⁺ were obtained, indicating that only 0.010 mol Cu were present in the mixture. This means that the acid was in excess, so we can assume that all copper present in the mixture has reacted.
Since 0.010 mol of Cu²⁺ were produced, the amount of Cu was 0.01 mol.
1 mol of Cu has a mass of 63.5 g, then 0.01 mol has a mass of:
0.01 mol Cu * 63.5 g / 1 mol = 0.635 g.
Since this amount was present in 2.00 g mixture, the amount of copper in 100 g of the mixture will be:
100 g(mixture) * 0.635 g Cu / 2 g(mixture) = 32 g
Then, the percent by mass of Cu (which is the mass of Cu in 100 g mixture) is 32%
