Question

the composition of the solution and the state of the light bulb (lit or unlit) is indicated by the data in the table.

solute	solubility in water	state of the light
sugar	very soluble	light bulb is not lit
starch	soluble	light bulb is not lit
potassium iodide	very soluble	light bulb is lit

what is the best explanation for the results shown in the table and why?

• a the sugar and starch solutions do not have a high enough concentration to allow the solution to conduct electricity.
• b the sodium chloride and potassium chloride and both very soluble, thus, the solutions have a high enough concentration to allow the solution to conduct electricity.
• c the sugar and starch dissolved in water to form positive and negative ions; however, the concentration of ions is not sufficient to conduct electricity.
• d the sodium chloride and potassium iodide dissolve to form positive and negative ions which allow the solution to conduct electricity.

Explanation:

To determine the best explanation, we analyze the conductivity of solutions. Ionic compounds (like NaCl, KI) dissociate into ions in water, allowing electricity conduction (light bulb lit). Covalent compounds (sugar, starch) dissolve as molecules, not ions, so they don't conduct.

• Option A: Concentration isn't the issue; sugar/starch are molecular. Eliminate.
• Option B: Solubility alone isn't the key; it's about ion formation. Eliminate.
• Option C: Sugar/starch don't form ions. Eliminate.
• Option D: Correctly explains that NaCl and KI dissociate into ions, enabling conductivity.

Answer:

D. The sodium chloride and potassium iodide dissolve to form positive and negative ions which allow the solution to conduct electricity.