Question

At STP, which of these substances is most soluble in H2O? (1) CCl4 (3) HCl (2) CO2 (4) N2

Answer 1

Answer: Option (3) is the correct answer.

Explanation:

It is known that like dissolves like that is, a polar solvent will dissolve only polar compounds. Whereas a non-polar solvent will dissolve only non-polar compound.

Substances whose atoms have large difference in electronegativities are polar in nature. Water is a polar solvent and it is able to dissolve polar molecules.  

For example, HCl is a polar or ionic compound so it is soluble in water.

On the other hand, $CCl_{4}$, $CO_{2}$, and $N_{2}$ are all non-polar as bond between them is formed due to sharing of electrons.

Hence, we can conclude that at STP, HCl is the substance that is most soluble in $H_{2}O$.

Answer 2

The correct answer is option 3. Hydrochloric acid is the most soluble in water at standard temperature and pressure because it is has a polar covalent bond which makes it a polar molecule. Water is also a polar substance therefore hydrochloric acid will really be soluble in water.