InterviewSolution
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InterviewSolution
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A domain in ferromagnetic iron is in the form of a ube of side length `2mum` then the number of iron atoms in the domain are `("Molecular mass of iron"= 55gmol^(-1) and "density"=7.92 g cm^(-3))`A. `6.92xx10^(12)"atoms"`B. `6.92xx10^(11)"atoms"`C. `6.92xx10^(10)"atoms"`D. `6.92xx10^(13)"atoms"` |
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Answer» Correct Answer - B The volume of the cubic domain `V=(2mu m)^(3)=(2xx10^(-6)m)^(3)` `=8xx10^(-18)m^(3)=8xx10^(-12)cm^(3)` and mass = volume `xx` density `= 8 xx 10^(-12) cm^(3) xx 7.9 g cm^(-3)` `=63.2xx10^(-12)g` Now the Avagadro number `(6.023xx10^(23))` of iron atoms have a mass of 55g. Hence the number of atoms in the domain are `N=(63.2xx10^(-12)xx6.023xx10^(23))/(55)=6.92xx10^(11)"atoms"` |
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