Question

The vapour pressure of a solution $(b)$ as a function of temperature $(a)$ is plotted as a graph for two solutions of same molar concentration along with water as shown below. $A,B$ and $C$ are respectively

• A. $H_{2}NCON{H}_2,H_{2}O,NaCl$
• B. $H_{2}O,H_{2}NCON{H}_2,NaCl$
• C. $NaCl,H_{2}O,H_{2}NCON{H}_2$
• D. $NaCl,H_{2}NCON{H}_2,H_{2}O$

Answer 1

Answer: (A)

The vapour pressure of a solution $(b)$ as a function of tcmpcraturc $(a)$ is plotted as a graph for two solutions of same molar concentration along with water.

Here, $A$ is $N{H}_2-\stackrel{\underset{||}{O}}{C}-N{H}_2$

$B$ is $H_{2}O$

$C$ is $NaCl$.



When number of moles of solute decreases, then vapour pressure of solution increases.

So, $H_{2}NCON{H}_2$ does not associate or dissociate.

$H_{2}O$ forms hydrogen bonding and associates vapour pressure increases. It dissociates to very small extent.

$NaCl$ dissociates, (as it is a strong electrolyte there number of moles increases therefore vapour pressure decreases.