Assume all salts are 90% dissociated which would have highest osmotic pressure 1) Decimolar aluminium sulphate 2) Decimolarbarium chloride 3) Decimolar sodium sulphate 4) solution obtained by mixing 2) & 3) and filtering

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Osmotic pressure, π=iCRTwhere, C=concentration of solute in moles per litrei= Vant Hoff factorNow, C, R, T is same for all the options, therefore, the osmotic pressure depends upon iFor Al2(SO4)3  Al2(SO4)3 2Al3+ + 3SO42-α=i-1(m-1)or 0.90=i-15-1or i-1=3.6or i=4.6For BaCl2BaCl2Ba2+ + 2Cl-α=i-1(m-1)or 0.90=i-13-1or i-1=1.8or i=2.8For Na2SO4Na2SO4 2Na+ + SO42-α=i-1(m-1)or 0.90=i-13-1or i-1=1.8or i=2.8For mixture of 2 and 3 i.e.BaCl2 + Na2SO4 BaSO4 + 2NaClThe BaSO4 forms precipitate and is filtered out. Now only NaCl is left in the solutionTherefore, i=2Since, i is greatest for (1), its osmotic pressure will also be highest.

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