solve 4 question
solve 4 question 1 rus of arrangement is not possible with the given radius ratio. A solid cubic crystal of edge length 15 mm of an ionic compound which has the rock salt type lattice, is added to 1 L of water (density 1 g cc) The freezing point of the solution found to be — 0.620C and degree of ionization of ionic compound is 60%(Given Kr of H20 = 1.86 kg/mol, 6 x 1023) 3. The correct figure given below, shows the location of anion ( type lattice BO in crystallographic face-diagonal plane corresponding the above unit cell is: 4. (C) Edge length of unit cell is (A) 300 pm (C) 600 pm (B) (B) 540 pm (D) 500 prn

Dear Student,

Tf= iKf.mSo, m=TfiKfTf=Tf°-Tf=0-(-0.62)=0.62°CFor rock salt type crystal, i= 1+α=1+0.60=1.6So, m=0.621.6×1.86=0.2Effective molality of solution = 0.2Now. Density=MassVolumeSo, Mass of water=Density×Volume=1 g/cm3×1000 cm3=1000 gHence, number of moles of ionic solid in given cube =Molality×Mass of water1000=0.2×10001000=0.2So, number of formula units in a given cube =0.2×6×1023Number of unit cells=14×0.2×6×1023=3×1022Number of units cells along one edge of cube =3×10223=3×107Edge length of unit cell, a=15×10-33×107=5×10-10 m=500×10-12m =500 pmHence, correct answer is (D)

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