Respuesta :
Answer:
The correct answer is option 3.
Explanation:
Molecular formula of the salt =[tex]MF_x[/tex]
The salt when dissolved in water will get dissociated into ions.
[tex]MF_x\rightarrow M^{x+}+xF^-[/tex]
van't Hoff factor = i = 1+x
Boiling point of the solution = [tex]T_b=374.38 K[/tex]
Boiling point of pure solvent that water = [tex]T=373.15 K[/tex]
Elevation in boiling point =[tex]\Delta T_b[/tex]
[tex]\Delta T_b=T_b-T=374.38 K-373.15 K=1.23 K[/tex]
[tex]\Delta T_b=i\times K_b\times m[/tex]
[tex]K_b[/tex]=molal elevation constant
m = molality of the solution
Molal elevation constant of water =0.52 K kg/mol
molality = [tex]\frac{\text{Mass of compound}}{\text{Molar mass of compound}\times \text{mas of solvent in kg}}[/tex]
[tex]m=\frac{9.18 g}{(96 g/mol+x\times 19 g/mol)\times 0.100 kg}[/tex]
[tex]1.23 K=i\times 0.52 K kg/mol\times \frac{9.18 g}{(96 g/mol+x\times 19 g/mol)\times 0.100 kg}[/tex]
i = 2.47+0.48x
2.47+0.48x = 1+x
x =2.8 ≈ 3
Molecular formula of the salt =[tex]MF_3[/tex]
