This is given by Avogagro number: 1 mol = 6.02*10^23 particles
Then you can do whichever to these two relations, because they are equivalent:
- 1mol / 6.02*10^23 representative particles, and
- 6.02*10^23 representative particle /1 mol
Only the second option of the question includes one of the valid conversion factors. Then, the conversion factor of the second option is the right answer
As a base is added to an acidic solution, the H+ ions in solution that make it acidic are slowly neutralized into water (via OH-, the base). As these ions are converted into water the concentration of them decreases, so the pH decreases, as they are directly related.
Hope this helps!
Increase at the temperature
Here try this presentation, it should help :)
https://prezi.com/6ofdo3fadl9a/exothermic-and-endothermic-reactions-in-everyday-life/
Answer: 0.20 M
Explanation:
According to the dilution law,

where,
= molarity of stock solution = 1.40 M
= volume of stock solution = 72.0 ml
= molarity of diluted solution = m
= volume of diluted solution = 248 ml


Now 124 mL portion of this prepared solution is diluted by adding 133 mL of water.
According to the dilution law,

where,
= molarity of stock solution = 0.41 M
= volume of stock solution = 124 ml
= molarity of diluted solution = m
= volume of diluted solution = (124 +133) ml = 257 ml


Thus the final concentration of the solution is 0.20 M.