Answer:
Iodoalkanes are very reactive because they have the weakest bond of C-I, thus they are most easily broken, making them most reactive. B. The carbon where the halogen is bonded is only attached to one other carbon.
Explanation:
 
        
             
        
        
        
Ionic compound are those compounds which are made up of ions. The ion which has tendency to loose electrons is said to cation (positive charge) such as metals whereas ion which has tendency to gain electrons is said to anion (negative charge) such as non-metals.
Calcium nitrate is quite soluble in water due to very low lattice enthalpy in comparison to other ionic compound. With lower lattice enthalpy, less energy is required for the dissociation of calcium nitrate and it get dissolves in water than other three compounds. Moreover, hydration energy is higher for calcium nitrate which make its solubility higher in water than other ionic species. 
Thus,  is correct answer.
 is correct answer.
 
        
             
        
        
        
We know that domestic dogs are descended from wolves. Exactly when and how this occurred is still being studied; many experts indicate that dogs were first domesticated about 12,000 years ago, but a few DNA studies indicate a much earlier date for the split between the wolf and the dog, perhaps as long ago as 130,000 years.
Regardless of the exact timing of the divergence between wolves and dogs, one thing is true: both species display quite a bit of genetic diversity, particularly in size and coloration.In order to breed a dog of a specific size, all one has to do is choose parents with the appropriate variations. For instance, if you want to create a small dog breed, you would just breed the smallest dogs you have, then you would choose their smallest offspring to breed the next generation, and so on until you have reached the desired size.