Question

Which of the following solutions in water will have the lowest vapour pressure.

• A. 0.1 M, NaCl
• B. 0.1 M, Sucrose
• C. 0.1 M, $\mathrm { BaCl } _ { 2 }$
• D. 0.1 M $\mathrm { Na } _ { 3 } \mathrm { PO } _ { 4 }$

Answer 1

Answer: (D)

0.1 M $\mathrm { Na } _ { 3 } \mathrm { PO } _ { 4 }$

Answer 2

$\mathrm { Na } _ { 3 } \mathrm { PO } _ { 4 }$ consist of maximum ions hence it show lowest vapour pressure.

$\mathrm { Na } _ { 3 } \mathrm { PO } _ { 4 } \rightarrow 3 \mathrm { Na } ^ { + } + \mathrm { PO } _ { 4 } ^ { 3 - } = 4$ion.