At standard pressure, a certain compound has a low boiling point and is insoluble in water. at stp, this compound most likely exists as
(1) ionic crystals
(2) metallic crystals
(3) nonpolar molecules
(4) polar molecules

Answer is (3) - nonpolar molecules.

Nonpolar molecules make weak attractions between molecules called van der Waals forces. Hence, they are looesly bound with each other. Therefore, nonpolar molecules can easily go to the atmosphere by breaking those weak bonds. Hence, the boiling point is low.

Since water is a polar solvent, nonpolar molecules do not soluble in water.

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.