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The molecular mass of a compound is 75 (i) Calculate the mass of 100 molecules, in amu. (ii) Calculate the mass of 5000 molecules , in gm. (iii) What is the mass of 6.022xx10^(20) molecules , in gm (iv) How many molecules are in its 2.5 mg |
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Answer» Solution :(i) mass of 1 molecules =75 amu `therefore` mass of 100 molecules=7500 amu (ii) Mass of 5000 molecules =`5000xx75` amu `=5000xx75xx1.67xx10^(-24)=6.26 25xx10^(-19)` gm `because 6.022xx10^(20)` molecules weights `(75)/(6.022xx10^(23))xx6.022xx10^(20)=0.075` gm (iv) `therefore `75 gm compound CONTAINS `6.022xx10^(23)` molecules `because 2.5xx10^(-3)` gm will contain `(6.022xx10^(23))/(75)xx2.5xx10^(-3)=2.007xx10^(19)` molecules. |
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