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Aluminium crystallises in a cubic close-packed structure. Its metallic radius is 125 pm. (i) What is the length of the side of the unit cell ? (ii) How many unit cells are there in 1.00 "cm"^3 of aluminium ? |
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Answer» Solution :Aluminum CRYSTALLIZE in a cubic close-packed structure. Its metallic radius is 125 pm. (i) In a cubic close-packed structure the edge length `(a) = 2sqrt(2)r` `= 2 xx 1.41 xx 125` = 354 pm. (ii) Volume of UNIT cell `= a^3 = (354)^3 xx 10^(-30) "cm"^3` `therefore` Number of unit CELLS in `1 "cm"^3` of aluminium`= (1)/((354)^3 xx 10^(-30))` `= 2.25 xx 10^(22)`. |
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