20555mg of a 1:1 electrolytes (mol. wt. = 100) are dissolved in 500g of water. The freezing point of the solution is −0.74oC, Kf=1.8K m−1. The degree of ionisation of electrolyte is:
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Solution
We know, ΔTf=Kf×mΔTf=1000×Kf×wM×W
Whre, w=weight of solute M=Molar mass of solute W=weight of solvent ∴0.74=1000×1.8×20.555M×500⇒M≈100
Now, Normal mol. wt.exp. mol. wt.=1+α=100100