Which of the following statements is NOT true in regards to water, ethanol, and isopropanol?

A. H-O-H and C-O-H bond angles are all equal to 109.5.

B. Dispersion forces affect all three molecules.

C. Two lone pairs of electrons are assigned to the oxygen in each Lewis structure of all three molecules.

D. Water has the highest boiling point.

E. All of these are true.

Choice A is incorrect.

True, A is not true. But isn't D not true also. I think, without looking it up, that ethanol has a lower boiling point than water. I remember something like 80 degrees C or so. And the question says statementS so it can have more than one answer. Check it out.

yes, I agree: both ethanol and isopropanol have LOWER boiling points than water.

Which of the following statements about the

boiling of water is NOT true?

1. Boiling occurs when the vapor pressure of
the water exceeds the atmospheric pressure.
2. The boiling point of water is unusually
high because of significant hydrogen bonding
in the molecule.
3. Spaghetti cooks more quickly in a pres-
sure cooker because the boiling point of water
increases.
4. The bubbles that form during boiling are
vapor from the water.

5. Spaghetti cooks more quickly in boiling
water at a high altitude because it is easier
for the vapor pressure to exceed atmospheric
pressure.

To determine which statement is not true, let's go through each option and analyze them one by one.

A. H-O-H and C-O-H bond angles are all equal to 109.5:
This statement is true for water (H2O) due to the tetrahedral geometry of the molecule. However, it is not true for ethanol (C2H5OH) and isopropanol (C3H7OH). Both ethanol and isopropanol have a tetrahedral carbon atom bonded to the oxygen atom, resulting in bond angles that deviate from 109.5 degrees.

B. Dispersion forces affect all three molecules:
This statement is true. Dispersion forces, also known as London dispersion forces, are present in all molecules and arise from temporary shifts in electron density that create temporary dipoles. Water, ethanol, and isopropanol all exhibit dispersion forces, although they are generally stronger in ethanol and isopropanol due to their larger molecular sizes.

C. Two lone pairs of electrons are assigned to the oxygen in each Lewis structure of all three molecules:
This statement is false. In the Lewis structure of water, oxygen has two lone pairs of electrons. However, in ethanol and isopropanol, the oxygen atom only has one lone pair of electrons.

D. Water has the highest boiling point:
This statement is true. Water has the highest boiling point among the three compounds. This is due to hydrogen bonding, a relatively strong intermolecular force that occurs between water molecules. Ethanol and isopropanol can also form hydrogen bonds, but they have lower boiling points compared to water.

Based on the analysis above, the statement that is NOT true is:
C. Two lone pairs of electrons are assigned to the oxygen in each Lewis structure of all three molecules.