Solutions · JEE Main previous year questions

Which purification technique is used for high boiling organic liquid compound (decomposes near its boiling point)?

1. A.Simple distillation
2. B.Steam distillation
3. C.Fractional distillation
4. D.Reduced pressure distillation

Which one of the following 0.06 M aqueous solutions has lowest freezing point?

1. A.$\mathrm{A}{\mathrm{l}}_2(\mathrm{S}{\mathrm{O}}_4{)}_3$
2. B.${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$
3. C.KI
4. D.${\mathrm{K}}_2\mathrm{S}{\mathrm{O}}_4$

2 molal solution of a weak acid HA has a freezing point of $-3.885^{\circ }\mathrm{C}$. The degree of dissociation of this acid is ____ $\times 10^{-3}$. (Round off to the Nearest Integer). [Given : Molal depression constant of water = $1.85\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$, Freezing point of pure water = $0^{\circ }\mathrm{C}$]

A solute A dimerizes in water. The boiling point of a 2 molal solution of A is $100.52^{\circ }\mathrm{C}$. The percentage association of A is ____. (Round off to the Nearest Integer). [Use : ${\mathrm{K}}_{\mathrm{b}}$ for water $=0.52\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$ Boiling point of water $=100^{\circ }\mathrm{C}$]

$\mathrm{A}{\mathrm{B}}_2$ is $10\%$ dissociated in water to ${\mathrm{A}}^{2+}$ and ${\mathrm{B}}^{-}$. The boiling point of a 10.0 molal aqueous solution of $\mathrm{A}{\mathrm{B}}_2$ is _______ ${}^{\circ }\mathrm{C}$. (Round off to the Nearest Integer). [Given : Molal elevation constant of water ${\mathrm{K}}_{\mathrm{b}}=0.5{\text{ K kg mol}}^{-1}$, boiling point of pure water $=100^{\circ }\mathrm{C}$]

$224\mathrm{mL}$ of $\mathrm{S}{\mathrm{O}}_{2(\mathrm{g})}$ at $298\mathrm{K}$ and $1\mathrm{atm}$ is passed through $100\mathrm{mL}$ of $0.1\mathrm{M}\mathrm{NaOH}$ solution. The non-volatile solute produced is dissolved in $36\mathrm{g}$ of water. The lowering of vapour pressure of solution (assuming the solution is dilute) $(P_{(H_{2}O)}^o=24\mathrm{mm}\mathrm{of}\mathrm{Hg})$ is $x\times 10^{-2}\mathrm{mm}\mathrm{of}\mathrm{Hg}$, the value of x is _________. (Integer answer)

When 12.2 g of benzoic acid is dissolved in 100 g of water, the freezing point of solution was found to be $-0.93^{\circ }\mathrm{C}$ (${\mathrm{K}}_{\mathrm{f}}({\mathrm{H}}_2\mathrm{O})=1.86\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$). The number (n) of benzoic acid molecules associated (assuming 100% association) is _________.

If a compound AB dissociates to the extent of 75% in an aqueous solution, the molality of the solution which shows a 2.5 K rise in the boiling point of the solution is ____ molal. (Rounded off to the nearest integer) $[{\mathrm{K}}_{\mathrm{b}}=0.52\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}]$

The elevation of boiling point of $0.10\text{ m}$ aqueous $\mathrm{CrC}{\mathrm{l}}_3\cdot \mathrm{xN}{\mathrm{H}}_3$ solution is two times that of $0.05\text{ m}$ aqueous $\mathrm{CaC}{\mathrm{l}}_2$ solution. The value of x is ______ . [Assume $100\%$ ionisation of the complex and $\mathrm{CaC}{\mathrm{l}}_2$, coordination number of Cr as 6, and that all $\mathrm{N}{\mathrm{H}}_3$ molecules are present inside the coordination sphere]

1. A.$\text{A}<\text{C}<\text{B}$
2. B.$\text{C}<\text{A}<\text{B}$
3. C.$\text{B}<\text{C}<\text{A}$
4. D.$\text{A}<\text{B}<\text{C}$

If the boiling point of ${\mathrm{H}}_2\mathrm{O}$ is 373 K, the boiling point of ${\mathrm{H}}_2\mathrm{S}$ will be :

1. A.greater than 300 K but less than 373 K
2. B.equal to 373 K
3. C.more than 373 K
4. D.less than 300 K

1. A.
2. B.
3. C.
4. D.

1. A.only (a) is true
2. B.(a), (b) and (c) are true
3. C.(b) and (c) are true
4. D.(a) and (b) are true

How much amount of $\mathrm{NaCl}$ should be added to 600 g of water ($\rho =1.00\text{ g/mL}$) to decrease the freezing point of water to $-0.2{}^{\circ }\mathrm{C}$ ? _______. (The freezing point depression constant for water $=2{\mathrm{K}\mathrm{kg}\mathrm{mol}}^{-1}$)

1. A.
2. B.
3. C.
4. D.

A solution is prepared by dissolving 0.6 g of urea ($\text{molar mass}=60{\text{ g mol}}^{-1}$) and 1.8 g of glucose ($\text{molar mass}=180{\text{ g mol}}^{-1}$) in 100 mL of water at $27^{\circ }\text{C}$. The osmotic pressure of the solution is : ($\text{R}=0.08206{\text{ L atm K}}^{-1}{\text{ mol}}^{-1}$)

1. A.8.2 atm
2. B.2.46 atm
3. C.4.92 atm
4. D.1.64 atm

1 g of a non-volatile non-electrolyte solute is dissolved in 100 g of two different solvents A and B whose ebullioscopic constants are in the ratio of 1 : 5. The ratio of the elevation in their boiling points, $\frac{\Delta T_b(A)}{\Delta T_b(B)}$, is :

1. A.5 : 1
2. B.1 : 0.2
3. C.10 : 1
4. D.1 : 5

The osmotic pressure of a dilute solution of an ionic compound XY in water is four times that of a solution of 0.01 M $\mathrm{BaC}{\mathrm{l}}_2$ in water. Assuming complete dissociation of the given ionic compounds in water, the concentration of XY (in $\mathrm{mol}{\mathrm{L}}^{-1}$) in solution is :

1. A.$4\times 10^{-4}$
2. B.$6\times 10^{-2}$
3. C.$4\times 10^{-2}$
4. D.$16\times 10^{-4}$

Liquid 'M' and liquid 'N' form an ideal solution. The vapour pressures of pure liquids 'M' and 'N' are 450 and 700 mmHg, respectively, at the same temperature. Then correct statement is: ($x_M$ = Mole fraction of 'M' in solution ; $x_N$ = Mole fraction of 'N' in solution ; $y_M$ = Mole fraction of 'M' in vapour phase ; $y_N$ = Mole fraction of 'N' in vapour phase)

1. A.$\frac{x_M}{x_N}<\frac{y_M}{y_N}$
2. B.$(x_M-y_M)<(x_N-y_N)$
3. C.$\frac{x_M}{x_N}=\frac{y_M}{y_N}$
4. D.$\frac{x_M}{x_N}>\frac{y_M}{y_N}$

Molal depression constant for a solvent is $4.0\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$. The depression in the freezing point of the solvent for $0.03\mathrm{mol}\mathrm{k}{\mathrm{g}}^{-1}$ solution of ${\mathrm{K}}_2\mathrm{S}{\mathrm{O}}_4$ is : (Assume complete dissociation of the electrolyte)

1. A.0.18 K
2. B.0.24 K
3. C.0.36 K
4. D.0.12 K

HF has highest boiling point among hydrogen halides, because it has :

1. A.lowest dissociation enthalpy
2. B.strongest hydrogen bonding
3. C.lowest ionic character
4. D.strongest van der Waals' interactions

1. A.
2. B.
3. C.
4. D.

Freezing point of a 4% aqueous solution of X is equal to freezing point of 12% aqueous solution of Y. If molecular weight of X is A, then molecular weight of Y is -

1. A.4A
2. B.2A
3. C.3A
4. D.A

Molecules of benzoic acid $({\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH})$ dimerise in benzene. 'w' g of the acid dissolved in 30 g of benzene shows a depression in freezing point equal to 2K. If the percentage association of the acid to form dimmer in the solution is 80, then w is – (Its given that $K_f=5\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$, Molar mass of benzoic acid = $122\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$)

1. A.1.5 g
2. B.1.8 g
3. C.1.0 g
4. D.2.4 g