Assuming the compounds to be completely dissociated in aqueous solution, identify the pair of the soltions which can be expected to be isotonic at the same temperature ?

Options

A. `0.01 M " urea and " 0.01 M NaCI`
B. `0.02 " M urea and 0.02 M Na_(2)SO_(4)`
C. `0.03 " M urea and " 0.02 M MgCI_(2)`
D. `0.01 "M surose and " 0.02 M " glucose "

Answer

c

Explanation

According to Van't Hoff equaiton for a dilution soltuion: `pi=iCRT`
For isotionic solution, `pi_(1)=pi_(2)` Since the two sloutions are at the same temperature, `i_(1)C_(1)RT=i_(2)C_(2)RT`
(a) For urea, `i_(1)=1, C_(1)=0.01M`
`"For" NaCI, i_(2)=2, C_(2)=0.01M`
`1xx0.01xxRT ne2xx0.01xxRT ("Not isotonic") `
(b)`" For" Naci, i_(1)=2,C_(1)-0.02M`
For `Na_(2)SO_(4), i_(2)=3, C_(2)=0.01 M`
`2xx0.02xxRTnr3xx0.01xxRT` ("Not isotonic")`
(c) For NaCI, `i_(1)=2, C_(1)=0.03 M`
For `MgCI_(2), i_(2)=3,C_(2)=0.02 M`
`2xx0.03 xxRT=3xx002xxRT`
(d) For sucrose, `i_(1)=1, C_(1)=0.01M`
For glucose, `i_(2)=1,C_(2)=0.02M`
`1xx0.01xxRT =2xx0.02xxRT` (Not isotonic)
is the correct answer.