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Calculate the mass of (i) 0.1 mole of KNO_(3) (ii) 1xx10^(23) molecules of methane and (iii) 112cm^(3) of hydrogen at STP. |
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Answer» Solution :(i) `"1 mole of "KNO_(3)=101g""(because" Formula mass of "KNO_(3)=1xx39+1xx14+3xx16=101u)` `therefore"0.1 mole of KNO"_(3)=101xx0.1` `=10.1" g OG "KNO_(3)` (ii) 1 mole of `CH_(4)=16g=6.022xx10^(23)` molecules i.e., `6.022xx10^(23)` molecules of methane have mass = 16 g `therefore""1xx10^(23)` molecules of methane will have meas`=(16)/(6.022xx10^(23))xx10^(23)=2.657g.` (iii) 1 mole of `H_(2)=2g=22400cm^(3)` at STP, i.e., 22400 `CM^(3)` of `H_(2)` at STP have mass = 2 g `therefore""112CM^(3)" of "H_(2)" at STP will have mass"=(2)/(22400)xx112=0.01g.` |
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