Answer: (3)
Medeleev arranged elements in order of increasing atomic weight and similar properties
He noticed that similar elements were grouped together by using this.
The main difference between concentration and density is that concentration refers to how much of a substance is present in a mixture, whereas density refers to the mass of a substance per unit volume.
Answer:
Observation
-I smell onions
-My dog weighs 45 pounds
-It is 85 degrees outside today
Predictions
-My dog will bark at the vacuum cleaner
although he has never seen it before
-My mother is going to cook spaghetti for
supper next Tuesday
-It will be a long, hot summer
Explanation:
The given question is incomplete. The complete question is as follows.
Sodium sulfate is slowly added to a solution containing 0.0500 M
and 0.0390 M
. What will be the concentration of
(aq) when
begins to precipitate? What percentage of the
can be separated from the Ag(aq) by selective precipitation?
Explanation:
The given reaction is as follows.

= 0.0390 M
When
precipitates then expression for
will be as follows.
![K_{sp} = [Ag^{+}]^{2}[SO^{2-}_{4}]](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%20%5BAg%5E%7B%2B%7D%5D%5E%7B2%7D%5BSO%5E%7B2-%7D_%7B4%7D%5D)
![1.20 \times 10^{-5} = (0.0390)^{2} \times [SO^{2-}_{4}]](https://tex.z-dn.net/?f=1.20%20%5Ctimes%2010%5E%7B-5%7D%20%3D%20%280.0390%29%5E%7B2%7D%20%5Ctimes%20%5BSO%5E%7B2-%7D_%7B4%7D%5D)
= 0.00788 M
Now, equation for dissociation of calcium sulfate is as follows.

![K_{sp} = [Ca^{2+}][SO^{2-}_{4}]](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%20%5BCa%5E%7B2%2B%7D%5D%5BSO%5E%7B2-%7D_%7B4%7D%5D)
![4.93 \times 10^{-5} = [Ca^{2+}] \times 0.00788](https://tex.z-dn.net/?f=4.93%20%5Ctimes%2010%5E%7B-5%7D%20%3D%20%5BCa%5E%7B2%2B%7D%5D%20%5Ctimes%200.00788)
= 0.00625 M
Now, we will calculate the percentage of
remaining in the solution as follows.

= 12.5%
And, the percentage of
that can be separated is as follows.
100 - 12.5
= 87.5%
Thus, we can conclude that 87.5% will be the concentration of
when
begins to precipitate.
Answer:
B. To Identify the half reactions for the equation