Answer
Al=143 pm
Zr=230 pm
the atomic radius difference is much larger than 15
They do not satisfy the first condition so they are not completely soluble.
Work Step by Step
For a substitutional solid solution having complete solubility, the following conditions must be satisfied:
1. Atomic radius difference must be less than 15.
2. Both have same electronegativity.
3. Both have same crystal structure.
4.Both have same valence electrons.
Al=143 pm
Zr=230 pm
the atomic radius difference is much larger than 15
They do not satisfy the first condition so they are not completely soluble.
