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.

Options

A. `H_(2)NCONH_(2), H_(2)O, NaCl`
B. `H_(2)O, H_(2)NCONH_(2), NaCl`
C. `NaCl, H_(2)O, H_(2)NCONH_(2)`
D. `NaCl, H_(2)NCONH_(2), H_(2)O`

Answer

A

Explanation

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.
Here, A is
B is `H_(2)O`.
C is NaCl.
When number of moles of solute decreases, then vapour pressure of solution increses.
So, `H_(2)NCONH_(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).