the students in ms. green's science class dissolved four salts in water. students varied water temperature to see if more or less salt would dissolve in a constant volume of water. changing the water temperature made little difference in the amount of dissolved in 100 grams of water.
a) kbr
b) kno
d) naclo3

C) NaCl

Explanation:

Its solubility is barely changing with temperature

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.