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A metallic element has a cubic lattice. Each edge of the unit cell is 2Å. The density of the metal is 2.5 g `cm^(-3)`.The unit cells in 200g of the metal areA. `1xx10^24`B. `1xx10^20`C. `1xx10^22`D. `1xx10^25` |
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Answer» Correct Answer - D Number of unit cell `=("mass of metal")/("mass of one unit cell")` Given, edge length of unit cell = 2Å `= 2xx10^(-8)` cm Mass of metal = 200 g Density of metal = `2.5gcm^(-3)` Volume of unit cell = `("edge length")^3=(2xx10^(-8))^3` `=8xx10^(-24)` Mass of one unit cell = volume x density `=8xx10^(-24) xx 2.5=20xx10^(-24)` `therefore` number of unit cell in 200 g metal `=("mass of metal")/("mass of one unit cell")=(200)/(20xx10^(-24))` `=10xx10^24=1.0xx10^25` |
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