<u>Answer:</u> The solubility of
in water is 
<u>Explanation:</u>
The balanced equilibrium reaction for the ionization of cadmium phosphate follows:

3s 2s
The expression for solubility constant for this reaction will be:
![K_{sp}=[Cd^{2+}]^3[PO_4^{3-}]^2](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BCd%5E%7B2%2B%7D%5D%5E3%5BPO_4%5E%7B3-%7D%5D%5E2)
We are given:

Putting values in above equation, we get:

Hence, the solubility of
in water is 
Answer:
A) The number of atoms in a grain of iron is most similar to the number of meters between Earth and Vega.
The options attached to the question are missing, but out of the numbers presented in the options, 10¹⁷ is closest to 10¹⁸.
B) The mass of a grain of iron is approximately (9 × 10⁻⁵) g
Explanation:
The options attached to the question are missing, after searching online, the image of the question was obtained, but it won't be attached to this solution in order not to violate the community guidelines and lead to deletion of answer.
But, out of the numbers presented in the options, 10¹⁷ is closest to 10¹⁸, hence, the number of atoms in a grain of iron is most similar to the number of meters between Earth and Vega.
The second part of the question asks for the approximate mass of a grain of iron.
1 atom of iron has a mass of (9 × 10⁻²³) g
1 grain of iron has about (1 × 10¹⁸) atoms of iron.
So, the mass of a grain of iron = (9 × 10⁻²³) × (1 × 10¹⁸) = (9 × 10⁻⁵) g
Hope this Helps!!!