Which one of the following is an isotonic pair of solution ?

Options

A. 0.15 M NaCI and `0.1 M Na_(2)SO_(4)`
B. 0.2 M urea and 0.1 M sugar
C. `0.1 M BaCI_(2)` and `0.1 M NH_(4)CI`
D. `0.2 M MgSO_(4)` and `0.1 M NH_(4)CI`

Answer

A

Explanation

`NaCI rarr Na^(+) + CI^(-)`
0.15 NaCI contains `0.15 xx 2 = 0.3 ` M particles
`NaSO_(4) rarr 2Na^(+) + SO_(4)^(2-)`
`:. 0.1 M Na_(2)SO_(4)` contains `0.1 xx 3 = 0.3` M particles
:. They are isotonic solutions.