Answer: A. Sodium chloride
Explanation: Sodium chloride ([tex]NaCl)[/tex] is an ionic compound formed by transfer of electrons from sodium to chlorine.
Electronic configuration of sodium:
[tex][Na]=1s^22s^22p^63s^1[/tex]
Sodium atom will loose one electron to gain noble gas configuration and form sodium cation with +1 charge.
[tex][Na^+]=1s^22s^22p^63s^0[/tex]
Electronic configuration of chlorine:
[tex][Cl]=1s^22s^22p^63s^23p^5[/tex]
Chlorine atom will gain one electron to gain noble gas configuration and form chloride ion with -1 charge.
[tex][Cl^-]=1s^22s^22p^63s^23p^6[/tex]
These ions can be separated in polar solvent water and thus are soluble in water.
Whereas methane ([tex]CH_4)[/tex] is a covalent compound formed by sharing of electrons and is soluble in non polar solvents.
Bromine [tex](Br_2)[/tex] is a covalent compound formed by sharing of electrons and is soluble in non polar solvents.
