D
Larger surface area speeds up reactions
Rust is an oxide so more oxygen should speed up rate of rust
Temperature also speeds up reactions
+ The humidity affects it aswell
Answer:
The molarity of the final solutions if these two solutions are mixed is 27.14 
Explanation:
Yo know:
- Solution-1: 25M, 400mL
- Solution-2: 30M, 300 mL
Molarity being the number of moles of solute per liter of solution, expressed by:

You can determine the number of moles that are mixed from each solution as:
Number of moles= Molarity*Volume
So, being 1 L=1000 mL, for each solution you get:
- Solution-1: being 0.400 L=400 mL ⇒ 25 M* 0.400 L= 10 moles
- Solution-2: being 0.300 L=300 mL ⇒ 30 M* 0.300 L= 9 moles
When mixing both solutions, it is obtained that the volume is the sum of both solutions:
Total volume= volume solution-1 + volume solution-2
and the number of total moles will be the sum of the moles of solution-1 and solution-2:
Total moles= moles of solution-1 + moles of solution-2
So the molarity of the final solution is:

In this case, you have:
- moles of solution-1: 10 moles
- moles of solution-2: 9 moles
- volume solution-1: 0.400 L
- volume solution-2: 0.300 L
Replacing:

Solving:

Molarity= 27.14 
<u><em>The molarity of the final solutions if these two solutions are mixed is 27.14 </em></u>
<u><em></em></u>
Answer:
1.096g
Explanation:
You must know the atomic mass of Hydrogen, Fluorine, and Sodium before you can start:
Hydrogen: 1.008g/mol
Fluorine: 18.99g/mol
Sodium: 22.98g/mol
Next, find the composition percentage of NaF
22.98 + 18.99 = 41.97
Fluorine is 18.99/41.97 =45.25%
Sodium is 100-45.25 = 54.75%
Ultimately we want to know about HF so find how much F is in 2.3g: 2.3 * 0.4525 = 1.041g
Find comp. percentage of HF
18.99+1.008 = 19.998; H/total F/total
Hydrogen 5.041%
Fluorine 94.959%
Laws of conservation of say we have 1.041g of fluorine in our HF. We know 1.041 is 94.959% of the mass of HF so do some simple math to find the remaining: 1.041/0.94959 = 1.096g