The student is now told that the four solids, in no particular order, are magnesium bromide (mgbr2), sugar (c6h12o6), butanoic acid (c3h7cooh), and potassium bromide (kbr). assuming that conductivity is correlated to the number of ions in solution, rank the four substances based on how well a 0.20 m solution in water will conduct electricity.

Magnesium chloride (MgCl₂) > Potassium bromide (KBr) > Butanoic acid (C₃H₇COOH) > Sugar (C₆H₁₂O₆)  (Conductivity)

Explanation:

The given samples:

Magnesium chloride (MgCl₂):

It is a strong salt which dissociates 100% into 3 ions, 1 Mg²⁺ and 2 Cl⁻

Sugar (C₆H₁₂O₆):

It is a carbohydrate and will have 0% dissociation and thus, no ions.

Butanoic acid (C₃H₇COOH):

It is a carboxylic acid (weak acids) which partially dissociates.

Potassium bromide (KBr):

It is a strong salt which dissociates 100% into 2 ions, K⁺ and Br⁻.

Thus, Conductivity is directly proportional to the numbers of ions dissociated in the solution and hence will conduct more electricity.

So,

Magnesium chloride (MgCl₂) > Potassium bromide (KBr) > Butanoic acid (C₃H₇COOH) > Sugar (C₆H₁₂O₆)  (Conductivity)