The plot given below shows `P -T` curves (where P is the pressure and T is the temperature) for two solvents X and Y and isomolal solutions of NaCl in these solvents. NaCl completely dissociates in both the solvents.

On addition of equal number of moles of a non-volatile solute S in equal amount (in kg) of these solvents, the elevation of boiling point of solvent X is three times that of solvent Y. Solute S is known to undergo dimerization in these solvents. If the degree of dimerization is 0.7 in solvent Y, the degree of dimerization in solvent X is ____.

Explanation

(0.05) From graph
For solven X' `" " Delta T_(bx)=2`
`Delta T_(bx)=m_(NaCl)xx K_(b(x))` …….(i)
For solvent ' Y' `" " Delta T_(by)=1`
`Delta T_(b(y))=m_(NaCl)xxK_(b(y))` …….(ii)
Equation (i)/(ii)
`rArr (K_(b(x)))/(K_(b(y)))=2`
For solute S
`underset(1-alpha)underset("1 ")(2(S))to underset(alpha-2)(S_(2))`
`i=(1-alpha//2)`
`Delta T_(b(x)(s))=(1-(alpha_(1))/(2))K_(b(x))`
`Delta T_(b(y)(s))=(1-(alpha_(2))/(2))K_(b(y))`
Given `Delta T_(b(x)(s))=3Delta T_(b(y)(s))`
`(1-(alpha _(1))/(2))K_(b(x))=3xx(1-(alpha_(2))/(2))xxK_(b(y))`
`2(1-(alpha_(1))/(2))=3(1-(alpha_(2))/(2))`
`alpha_(2)=0.7`
So `alpha_(1)=0.05` .