Question

which of the following molecules does not have a polar region?
a water
b triglyceride
c water-soluble amino acid
d glucose

question 38

the ph scale measures the
a concentration of hydrogen ions in solution.
b number of molecules of salts dissolved in water.
c number of hydroxide ions in water.
d strength of an electrical current that a solution carries.

Explanation:

First Question (Molecule with no polar region)

• Water ($\ce{H2O}$) is polar due to its bent shape and electronegativity difference between O and H, creating a polar region.
• Triglycerides are lipids, mostly non - polar (composed of fatty acid tails which are non - polar hydrocarbon chains and a glycerol head, but overall the non - polar part dominates and they are considered non - polar or have very little polar character compared to the others here).
• Water - soluble amino acids have polar groups (like carboxyl and amino groups) that make them water - soluble, so they have a polar region.
• Glucose has multiple hydroxyl ($\ce{-OH}$) groups which are polar, so it has a polar region.

• The pH scale is defined as $pH = -\log_{10}[\ce{H+}]$, where $[\ce{H+}]$ is the concentration of hydrogen ions in solution. So it measures the concentration of hydrogen ions in solution.
• Option B is wrong because pH is not related to the number of salt molecules dissolved.
• Option C is wrong as pH is related to $\ce{H+}$ (and $\ce{OH-}$ indirectly through $K_w = [\ce{H+}][\ce{OH-}]$), but it does not directly measure the number of $\ce{OH-}$ ions.
• Option D is wrong as pH has nothing to do with the strength of an electrical current a solution carries.

Answer:

B. Triglyceride

Second Question (pH scale measurement)