It is B, and also for a moment I didn't understand that 4.69 x 10^22. I almost did this whole problem wrong.
Answer:
Explanation: Mendeleev arranged the elements on the basis of their atomic mass. Melting and boiling point were used as the physical characteristics in deciding the position of elements. He arranged the elements and wrote the formula of their oxides and hydrides which seemed to possess same chemical formula.
Explanation:
A covalent bond would be difficult to disrupt when the compounds are placed in water.
I believe number 26 if in correct is product.
If you are balancing the equation, your final one should be
Cu3(PO4)2 +6 NaCl.
The reaction is a double replacement reaction