The addition of `CaCl_(2)` crystal to `KCl` crystal
a. Lowers the density of the `KCl` crystal
b. Raises the density of the `KCl` crystal
c. Does not affect the density of the `KCl` crystal
d. Increases the Frenkel defects of the `KCl` crystal

Explanation

a. One `Ca^(2+)` lets two `K^(Å)` leave the crystal to maintain the electrical neutrality of the compound.
The mass of two `K^(Å)` is greater than the mass of `Ca^(2+)`.
Hence, density decreases.