a) ionic
chlorine is present in top of group 17 and right of period 3 and
electronegativity(the tendency to gain electrons)
increases up the group and right the group.
so it has high tendency to form anion.
In the same way both Na and K are present up the group and left side and the tendency to lose electrons in both becomes high and they tend to form cation.
Solubility is the property of a solid/liquid/gaseous chemical substance called the solute, to dissolve in a solvent thus forming a homogeneous solution. Generally the solvent …is a liquid. Solubility of a substance fundamentally depends on the solvent used, the temperature and pressure