Answer:
The correct answer is 1 millon years.
Explanation:
Fossil rocks serve to study the evolution of species throughout history. Species usually adapt to survive the changing environment around them. Given this fact, we can deduce that the oldest species were very different from the way they are today. This means that the current species are more similar to those that preceded them more recently. The fossil of 1 million years ago is the most similar to today's horse.
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The trend of atomic radius in the periodic table is increasing from right to left and from top to bottom. In reference to the table, oxygen has smaller radius compared to carbon, which is smaller than aluminum and which is also smaller than potassium. Thus, the trend from smallest to biggest is oxygen carbon, aluminum and potassium.
Answer: can be made up of one atom with several different elements in it (b)
Explanation:
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Explanation:
It is given that aluminium nitrate and calcium chloride are mixed together with sodium phosphate.
And,
Let us assume that the solubility be "s". And, the reaction equation is as follows.

s = 
Also, 

s = 
This means that first, aluminium phosphate will precipitate.
Now, we will calculate the concentration of phosphate when calcium phosphate starts to precipitate out using the
expression as follows.
![K_{sp} = [Ca^{2+}]^{3}[PO^{3-}_{4}]^{2}](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%20%5BCa%5E%7B2%2B%7D%5D%5E%7B3%7D%5BPO%5E%7B3-%7D_%7B4%7D%5D%5E%7B2%7D)
![2.0 \times 10^{-29} = (0.016)^{3}[PO^{3-}_{4}]^{2}](https://tex.z-dn.net/?f=2.0%20%5Ctimes%2010%5E%7B-29%7D%20%3D%20%280.016%29%5E%7B3%7D%5BPO%5E%7B3-%7D_%7B4%7D%5D%5E%7B2%7D)
![2.0 \times 10^{-29} = 4.096 \times 10^{-6} \times [PO^{3-}_{4}]^{2}](https://tex.z-dn.net/?f=2.0%20%5Ctimes%2010%5E%7B-29%7D%20%3D%204.096%20%5Ctimes%2010%5E%7B-6%7D%20%5Ctimes%20%5BPO%5E%7B3-%7D_%7B4%7D%5D%5E%7B2%7D)
= 
=
M
Similarly, calculate the concentration of aluminium at this concentration of phosphate as follows.

![K_{sp} = [Al^{3+}][PO^{3-}_{4}]](https://tex.z-dn.net/?f=K_%7Bsp%7D%20%3D%20%5BAl%5E%7B3%2B%7D%5D%5BPO%5E%7B3-%7D_%7B4%7D%5D)
![9.84 \times 10^{-21} = [Al^{3+}] \times 2.21 \times 10^{-12}](https://tex.z-dn.net/?f=9.84%20%5Ctimes%2010%5E%7B-21%7D%20%3D%20%5BAl%5E%7B3%2B%7D%5D%20%5Ctimes%202.21%20%5Ctimes%2010%5E%7B-12%7D)
M
Thus, we can conclude that concentration of aluminium will be
M when calcium begins to precipitate.