Question

Which of the following substances is the most soluble in water?

Answer 1

A. Sodium Chloride.

Answer 2

Answer: A. Sodium chloride

Explanation: Sodium chloride ($NaCl)$ is an ionic compound formed by transfer of electrons from sodium to chlorine.

Electronic configuration of sodium:

$[Na]=1s^22s^22p^63s^1$

Sodium atom will loose one electron to gain noble gas configuration and form sodium cation with +1 charge.

$[Na^+]=1s^22s^22p^63s^0$

Electronic configuration of chlorine:

$[Cl]=1s^22s^22p^63s^23p^5$

Chlorine atom will gain one electron to gain noble gas configuration and form chloride ion with -1 charge.

$[Cl^-]=1s^22s^22p^63s^23p^6$

These ions can be separated in polar solvent water and thus are soluble in water.

Whereas methane ($CH_4)$ is a covalent compound formed by sharing of electrons and is soluble in non polar solvents.

Bromine $(Br_2)$ is a covalent compound formed by sharing of electrons and is soluble in non polar solvents.