When `10 mL` of ehtyl alcohol (density `= 0.7893 g mL^(-1))` is mixed with `20 mL` of water (density `0.9971 g mL^(-1))` at `25^(@)C`, the final solution has a density of `0.9571 g mL^(-1)`. The percentage change in total volume on mixing is

Options

A. `3.1%`
B. `2.4%`
C. `1%`
D. None of these

Answer

A

Explanation

Total weight of alcohol and water
`= 10 xx 0.7893 + 20 xx 0.9971`
Volume of mixture `= (10 xx 0.7893 + 20 xx 0.9971)/(0.9571)`
`= 29.08 mL`
Change in volume `= (20 + 10) - 29.08`
`= 0.92 mL` ltbgt %change in volume `= (0.92 xx 100)/(30) = 3.06 %`
`~~ 3.1%`