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`A_(2)B` molecules`(" molar mass " = 259.8 g//"ml")` crystallises in a hexagonal lattice as shown in figure .The lattic constants were `a=5 Å` and `b=8 Å` . If denstiy of crystal is `5 g//cm^(3)` then how many molecules are contained in given unit cell ? `(" Use" N_(A) = 6xx10^(23))` |
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Answer» Correct Answer - 2 Volume of unit cell `=a^2 sin 60xxb` `=173.2xx10^(-24) cm^3` Mass of unit cell `=173.2xx10^(-24)xx5xx6xx10^(23)` No of molecules in unit cell `=519.6/259.8=2` |
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