Molarity of 20% `(v//v) C_(2)H_(5)OH` solution in water is :
[Assume voume is additive and density of solution is `1.03 gm//ml` and of water is `1 gm//"ral"` ]

Options

A. 0.5 M
B. 5 M
C. 2.5 M
D. 1.25 M

Answer

B

Explanation

`20% ((v)/(v)) C_(2)H_(5)OH`
`20 mL` of `C_(2)H_(5)OH` in 100 ml solution
solution
`V = 100 ml`
`m = V xx d = 100 xx 1.03 = 103 gm`
Solvent
`V = 80 ml`
`m = 80 xx 1 = 80 gm`
mass of slute `= 103 - 80 = 23 gm`
`M = ("moles of solute")/("volune of solution of litre")`
`M = (23)/(46) xx (1000)/(100) = 5 M`