Two samples of `HCl` of `1.0 M` and `0.25 M` are mixed. Find volumes of these samples taken in order to prepare `0.75 M HCl` solution. Assume no water is added.
(I) `20 mL, 10 mL` (II) `100 mL, 50 mL`k
(III) `40 mL, 20 mL` (IV) `50 mL, 25 mL`

Options

A. I,II,IV
B. I,II
C. II,III,IV
D. I,II,III,IV

Answer

D

Explanation

`M_(1) = 1.0 M, M_(2) = 0.25 M`
Let `V_(1)` and `V_(2)` are volumes required
`(1.0 xx V_(1) + 0.25 xx V_(2)) = 0.75 (V_(1) + V_(2))`
`implies 0.25 V_(1) = 0.5 V_(2), implies V_(1) : V_(2) = 2:1`