Solutions · JEE Main previous year questions

${\mathrm{K}}_2\mathrm{Hg}{\mathrm{I}}_4$ is 40% ionised in aqueous solution. The value of its van't Hoff factor (i) is:

1. A.1.6
2. B.2.2
3. C.2.0
4. D.1.8

Which one of the following statements regarding Henry's law is not correct ?

1. A.Higher the value of ${\mathrm{K}}_{\mathrm{H}}$ at a given pressure, higher is the solubility of the gas in the liquids
2. B.Different gases have different ${\mathrm{K}}_{\mathrm{H}}$ (Henry's law constant) values at the same temperature.
3. C.The partial pressure of the gas in vapour phase is proportional to the mole fraction of the gas in the solution.
4. D.The value of ${\mathrm{K}}_{\mathrm{H}}$ increases with increase of temperature and ${\mathrm{K}}_{\mathrm{H}}$ is function of the nature of the gas

For 1 molal aqueous solution of the following compounds, which one will show the highest freezing point?

1. A.$[\text{Co}({\text{H}}_2\text{O}{)}_3{\text{Cl}}_3].3{\text{H}}_2\text{O}$
2. B.$[\text{Co}({\text{H}}_2\text{O}{)}_6]{\text{Cl}}_3$
3. C.$[\text{Co}({\text{H}}_2\text{O}{)}_5\text{Cl}]{\text{Cl}}_2.{\text{H}}_2\text{O}$
4. D.$[\text{Co}({\text{H}}_2\text{O}{)}_4{\text{Cl}}_2]\text{Cl}.2{\text{H}}_2\text{O}$

The increasing order of the boiling points for the following compounds is : $$\begin{array}{cccc}{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}& {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Cl}& {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{C}{\mathrm{H}}_3& {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OC}{\mathrm{H}}_3\\ \text{(I)}& \text{(II)}& \text{(III)}& \text{(IV)}\end{array}$$

1. A.(III) < (IV) < (II) < (I)
2. B.(IV) < (III) < (I) < (II)
3. C.(II) < (III) < (IV) < (I)
4. D.(III) < (II) < (I) < (IV)

5 g of $\mathrm{N}{\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$ was dissolved in x g of ${\mathrm{H}}_2\mathrm{O}$. The change in freezing point was found to be $3.82^{\circ }\mathrm{C}$. If $\mathrm{N}{\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$ is 81.5% ionised, the value of x (${\mathrm{K}}_{\mathrm{f}}$ for water=$1.86^{\circ }\mathrm{C}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$) is approximately : (molar mass of $\mathrm{S}=32\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ and that of $\mathrm{Na}=23\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$)

1. A.$15\mathrm{g}$
2. B.$25\mathrm{g}$
3. C.$45\mathrm{g}$
4. D.$65\mathrm{g}$

Which one has the highest boiling point?

1. A.Ne
2. B.Kr
3. C.Xe
4. D.He

The freezing point of a $1.00\mathrm{m}$ aqueous solution of $\mathrm{HF}$ is found to be $-1.91^{\circ }\mathrm{C}$. The freezing point constant of water, $K_f$ is $1.86\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$. The percentage dissociation of $\mathrm{HF}$ at this concentration is

1. A.$30\%$
2. B.$10\%$
3. C.$5.2\%$
4. D.$2.7\%$

If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water ($\Delta {\mathrm{T}}_f$), when 0.01 mol of sodium sulphate is dissolved in 1 kg of water, is (${\mathrm{K}}_f=1.86\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$)

1. A.0.0372 K
2. B.0.0558 K
3. C.0.0744 K
4. D.0.0186 K

On mixing, heptane and octane form an ideal solution. At 373 K, the vapour pressures of the two liquid components (heptane and octane) are 105 kPa and 45 kPa respectively. Vapour pressure of the solution obtained by mixing 25.0g of heptane and 35 g of octane will be (molar mass of heptane = $100\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ and of octane = $114\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$)

1. A.72.0 kPa
2. B.36.1 kPa
3. C.96.2 kPa
4. D.144.5 kPa

Two liquids X and Y form an ideal solution. At 300K, vapour pressure of the solution containing 1 mol of X and 3 mol of Y is 550 mm Hg. At the same temperature, if 1 mol of Y is further added to this solution, vapour pressure of the solution increases by 10 mm Hg. Vapour pressure (in mm Hg) of X and Y in their pure states will be, respectively :

1. A.200 and 300
2. B.300 and 400
3. C.400 and 600
4. D.500 and 600

Which one of the following has the minimum boiling point?

1. A.n-butane
2. B.isobutane
3. C.1- butene
4. D.1- butyne

Which one of the following aqueous solutions will exhibit highest boiling point?

1. A.0.01 M $\mathrm{N}{\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$
2. B.0.015 M glucose
3. C.0.015 M urea
4. D.0.01 M $\mathrm{KN}{\mathrm{O}}_3$

Which of the following liquid pairs shows a positive deviation from Raoult’s law?

1. A.Water – hydrochloric acid
2. B.Acetone – chloroform
3. C.Water – nitric acid
4. D.Benzene – methanol

If an endothermic reaction is non-spontaneous at freezing point of water and becomes feasible at its boiling point, then :

1. A.$\Delta H$ is -ve, $\Delta S$ is +ve
2. B.$\Delta H$ and $\Delta S$ are both +ve
3. C.$\Delta H$ and $\Delta S$ are both -ve
4. D.$\Delta H$ is +ve, $\Delta S$ is -ve

Freezing point of an aqueous solution is $(-0.186{)}^{\circ }\mathrm{C}$. Elevation of boiling point of the same solution is $K_b=0.512{}^{\circ }\mathrm{C}$, $K_f=1.86{}^{\circ }\mathrm{C}$, find the increase in boiling point.

1. A.$0.186{}^{\circ }\mathrm{C}$
2. B.$0.0512{}^{\circ }\mathrm{C}$
3. C.$0.092{}^{\circ }\mathrm{C}$
4. D.$0.2732{}^{\circ }\mathrm{C}$