The number of molecules in a drop of water (0.0018 ml) at room tempera

1.	The number of molecules in a drop of water (0.0018 ml) at room temperature is
Answer» SOLUTION :0.0018 ml - drop of water = 0.0018 g H2O = molecular mass = 18 g. Number of molecules in 18 g = `6.023 xx 10^(23)` Number of molecules in 0.0018 g = `(6.023xx10^(23))/18 xx 0.0018 = 6.023xx10^(23)xx10^(-5)` `= 6.023xx10^(19)` molecules. [OR] DENSITY of water at `25^@` C=997.0479 g/L Mass of 0.0018 ml (or) `0.0018xx10^(-3)L` `=DXXV` `=997.05xx0.0018xx10^(-3)` `=1.795xx10^(-3)g` Molar mass of water = 18 g Mole=`(1.795xx10^(-3))/18=9.971xx10^(-5)` mole `:.`Number of molecules in 0.0018 ml= moles `xx` Avogadro number `9.971xx10^(-5)xx6.023xx10^(23)` `6xx10^(19)` molecules

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