the answer is A convalent
Melting point- the temperature at which a substance has changed from a solid to a liquid
freezing- the temperature at which a substance chanes from liquid to a solid
boiling point- the temperature at which a substance changes from a liquid to a gas phase
Your independent variable would be salt because it doesn't change the only thing that changes is the water.
Skeletal Equation
Ba(NO3)2 + KCl = BaCl2+ KNO3
Balanced equation
Ba(NO3)2 + 2KCl = BaCl2 + 2KNO3