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

A. Two lone pairs of electrons are assigned to the oxygen in each Lewis structure of all three molecules.
B. H-O-H and C-O-H bond angles are all equal to 1095.
C. Dispersion forces affect all three molecules.
D. Water has the highest boiling point.
E. All of these are true.

I don't know the bond angles for COH in ethanol and isopropanol but I know the bond angle in water is 105 degrees so I would pick B. By the way, I'm sure you intended to write 109.5 and not 1095 and you omitted the units.

To determine which statement is NOT true, let's evaluate each of the given options:

A. Two lone pairs of electrons are assigned to the oxygen in each Lewis structure of all three molecules.
To validate this statement, you can draw the Lewis structures of water (H2O), ethanol (C2H5OH), and isopropanol (CH3CHOHCH3). By doing this, you will see that two lone pairs of electrons are indeed assigned to the oxygen atom in each molecule. Hence, statement A is true.

B. H-O-H and C-O-H bond angles are all equal to 109.5°.
To verify this statement, you can find the VSEPR (Valence Shell Electron Pair Repulsion) structures of water, ethanol, and isopropanol. Water has a bent or V-shaped structure due to its two lone pairs of electrons, resulting in H-O-H bond angles close to 104.5°. Ethanol and isopropanol have a tetrahedral structure around the central oxygen atom, resulting in C-O-H bond angles close to 109.5°. Therefore, statement B is not true as the bond angles are different.

C. Dispersion forces affect all three molecules.
Dispersion forces, or London dispersion forces, exist between all molecules, regardless of their polarity. Since all three molecules (water, ethanol, and isopropanol) are composed of atoms with electrons, they will experience dispersion forces. Thus, statement C is true.

D. Water has the highest boiling point.
Water molecules are capable of forming extensive hydrogen bonding due to the presence of hydrogen atoms bonded to an electronegative oxygen atom. Hydrogen bonding is a strong intermolecular force that significantly increases the boiling point of water compared to other molecules with similar molecular weights. Ethanol and isopropanol can also form hydrogen bonds but to a lesser extent. Therefore, water having the highest boiling point among the three is true, making statement D valid.

E. All of these are true.
Since we have identified that statement B is not true, statement E, which states that all of the statements are true, is incorrect.

Hence, the correct answer is B. H-O-H and C-O-H bond angles are all equal to 109.5°.