Answer:
Water near the poles often have higher salinity because Cold polar air cools the water and lowers its temperature, increasing its salinity. Fresh water freezes out of seawater to become sea ice, which also increases the salinity of the remaining water.
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Method 1: gravimetry
advantages: Impurities in the sample can be identified
disadvantages: The process is long, because it goes through several stages
Method 2: titration
advantages: the process is fast, because the titrate and titrant react immediately
disadvantages: Sometimes the determination of the end point of the titration is carried out too fast or too slowly so that the calculations carried out are inaccurate
The subscript 2 indicate that there are two atoms of chlorine in the compound.
<u><em> Explanation</em></u>
Subscript in the chemical formula indicate the number of atoms of the element immediately before the subscript.
In MgCl₂ there are two(2) atoms of chlorine since Subscript 2 is immediately after chlorine.
Answer:

Explanation:
Hello,
In this case, for first order reactions, we can use the following integrated rate law:
![ln(\frac{[A]}{[A]_0} )=kt](https://tex.z-dn.net/?f=ln%28%5Cfrac%7B%5BA%5D%7D%7B%5BA%5D_0%7D%20%29%3Dkt)
Thus, we compute the time as shown below:
![t=-\frac{ln(\frac{[A]}{[A]_0} )}{k}=- \frac{ln(\frac{0.220M}{0.690M} )}{0.55s^{-1}} \\\\t=-\frac{-1.14}{0.550s^{-1}}\\ \\t=2.08s](https://tex.z-dn.net/?f=t%3D-%5Cfrac%7Bln%28%5Cfrac%7B%5BA%5D%7D%7B%5BA%5D_0%7D%20%29%7D%7Bk%7D%3D-%20%5Cfrac%7Bln%28%5Cfrac%7B0.220M%7D%7B0.690M%7D%20%29%7D%7B0.55s%5E%7B-1%7D%7D%20%5C%5C%5C%5Ct%3D-%5Cfrac%7B-1.14%7D%7B0.550s%5E%7B-1%7D%7D%5C%5C%20%5C%5Ct%3D2.08s)
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