InterviewSolution
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InterviewSolution
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By X-ray studies, the packing atoms, in a crystal of gold is found to be in layers such that starting from any layer, every fourth layer is found to be exactly idenctical. The density of gold is found to be ` 19.4 g cm^(-3)` and its atomic mass is 197 a.m.u. The length of the edge of the unit cell will beA. 407 pmB. 189 pmC. 814 pmD. 204 pm |
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Answer» ` p = (Z xx M)/( a^(3) xx N_(0) xx 10^(-30)) or a^(3) = (Z xx M)/( p xx N_(0) xx 10^(-30))` For ccp , i.e, f.c.c , Z= 4 Hence , ` a^(3) = ( 4 xx 197)/( 19.4 xx 6.02 xx 10^(23) xx 10^(-30))` ` = 6.747 xx 10^(7) = 67.47 xx 10^(6)` ` a = (67.47)^(1//3) xx 10^(2)` ` 4.07 xx 10^(2) "pm" = 407 "pm"` |
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