how does young modulus depend on Ro in alkali halide compounds. Show mathematically and derive an expression for the same.

A B Slope - . F--alrM-b/rN mo Force Force Elastic range Force between atoms as a function of the interatomic spacing. (A) Plot of F = dU/dr versus r. (B) Plot of F + dU/dr versus r. The range of elastic response is indicated. VALUES OF MELTING POINT (TH), BINDING ENERGY (U.), YOUNG'S MODULUS (EX), AND COEFFICIENT OF THERMAL EXPANSION (a) FOR SELECTED MATERIALS Material T (C) U (kJ/moly E, (GPa) a (10--') 49 7657 688" 988* 3891* 211*** 198*** 269*** 40 100 413 436** 612 603 879** 167493 749 Naci LIF MgO Sio ALLO, SINA WC Diamond SI Ge AI Cu ts W Polyethylene Nylon 801 776 842 2800 1710 2980 1900 2776 4350 1415 937 660 1083 1534 3410 112 293 94 379 310 720 1050 166 129 70 115 205 384 -0.35 -2.8 13.5 0.5 8.8 2.5 4.0 1 3 713*** 366*** 384*** 319*** 338 398*** -770*** 22 17 12 4.4 -150 -100 "The three measures of U, are physically different: * Energy liberated upon formation from the tons at 298 K. ** Hear liberated upon formation from the elements (atoms) at 298 K. *** Heat of sublimation