I can think of 2 cases: one is exemplified by the ammonium hydroxide which forms upon dissolution of gaseous ammonia in water as shown in the equation

NH3 + H2O   NH4+OH- . In this case, the gas concentration can be found easily from the aqueous concentration of the hydroxide & both will have the same value.

The other case is when a gas undergoes "physical" dissolution with no interaction as above (e.g. mehanolamine captures gaseous carbon dioxide dissolving it). Here, Henry's law applies:

"At a constant T, the amount of a given gas that dissolves in a given type & volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid." In other words, the concentration or solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid:

C=k. Pgas

where C is the solubility or conc'n of a gas at a fixed T in a particular solvent (in units of M or mL gas/L)

k is Henry's law constant (often in units of M/atm)

Pgas is the partial pressure of the gas (often in units of atm)

You may find useful to check the following somewhat related discussion: https://www.researchgate.net/post/How_does_Henrys_constant_change_with_salt_concentration/1

The following discussions specifically address the salting-out effect: https://www.researchgate.net/post/Why_when_i_add_NaCl_1_in_aqueous_solution_of_PEG_10_it_doesnt_disolve_cellulose_acetate_anymore https://www.researchgate.net/post/Does_anyone_have_the_Setschenow_salting_out_constant_of_N2O

While considering the water vapour concentration in the gas phase, maybe my post at the following discussion, addressing aqueous solution of LiBr, can also be found of some help: https://www.researchgate.net/post/How_does_an_aqueous_lithium_bromide_solution_absorb_water_vapour

www.mhhe.com/physsci/chemistry/chang7/ssg/chap14_5sg.html

Above link may be useful.

Thank you Nizar Matar, Carlos Araújo Queiroz and Anirbid Sircar , for the answers . It is very helpful to me.

But i've a doubt,

Suppose i have taken 1 ppm of toluene ( aqueous solution ), now i want to know will the concentration in gaseous state ( vapours ) will remain 1 ppm or not ? because i am having a doubt  that toluene boiling point is 110 C , and at room temperature 22 C it wont vapourize . so what concentration of toluene will be mixed with air inside the chamber ?