The density of water and ethanol at room temperature is 1.0 g/mL and 0.789 g/mL respectively. What volume of ethanol contains the same number of molecules as are present in 100 mL of water?

Options

A. 323.9 mL
B. 3.23 mL
C. 30.8 mL
D. 308.7 mL

Answer

A

Explanation

Equal number of moles contain equal number of molecules.
` (" Weight of "C_2 H_5 OH )/( " Molecular weight of "C_2 H_5 OH) = (" weight of " H_2O)/( "Molecular weight of " H_2 O)`
`(0.789 xx " volume of "C_2 H_5 OH)/( 46 ) = (1.0 xx 100)/(18)`
volume of `C_2 H_ 5 OH = (100)/(18 ) xx (46 )/(0.789 ) = 323.9 mL`