AIIMS Chemistry Solutions Class 12 Questions

Out of $\text{BeF}_2, \text{MgF}_2, \text{CaF}_2, \text{SrF}_2$ which has maximum solubility :

If Boiling point of water is 100°C. How much gram of NaCl is added in 500 g of water to increase its boiling point of water by approx 1°C. (K_b)H₂O = 0.52 K kg/mole.

Assertion: Some salts are sparingly soluble at room temperature. Reason: The entropy increases on dissolving the salts.

The vapour pressure of pure $\text{CHCl}_3$ and $\text{CH}_2\text{Cl}_2$ are 200 and 41.5 atm respectively. The weight of $\text{CHCl}_3$ and $\text{CH}_2\text{Cl}_2$ are resepectively 11.9 g and 17 gm. The vapour pressure of solution will be

Vapour pressure of $\text{CCl}_4$, at 25°C is 143 mm Hg. 0.5 g of a non-volatile solute (mol. wt. 65) is dissolved in 100 mL of $\text{CCl}_4$, Find the vapour pressure of the solution. ($\text{Density of CCl}_4, = 1.58\text{ g/cm}^3$)

Calculate Molarity of a 63% w/w $\text{HNO}_3$ solution if density is $5.4\text{ g/mL}$:

In isolated system, find the condition for spontaneous reaction.

Assertion : Reverse osmosis is used for desalination of sea water. Reason : Reverse osmosis occurs when a pressure larger than the osmotic pressure is applied to the solution.

Assertion : Ideal solutions obey Raoult's law. Reason : $\Delta\text{H}_{\text{mix}}$ and $\Delta\text{V}_{\text{mix}}$ for an ideal solution are less than zero.

Assertion : The alkali metal dissolves in liquid $\text{NH}_3$, giving deep blue solution. Reason : Blue colour of the solution is due to the ammoniated electron which absorbs energy in visible region of light.

When 45 g solute is dissolved in 600 g water, freezing point lowered by 2.2 K, calculate molar mass of solute (kₓ = 1.86 K kg mol⁻¹).

Freezing point of $0.4\text{ m}$ solution of a weak monoprotic acid is $-0.1^\circ\text{C}$. What is its van 't Hoff factor $i$ ?

$1\text{ gm}$ of polymer having molar mass $1,60,000\text{ gm}$ dissolve in $800\text{ ml}$ water, so calculate osmotic pressure in pascal at $27\ ^\circ\text{C}$($R = 8.314\text{ J/K mole}$)

Ethylene glycol is used as antifreeze to reduce the freezing point of water to $-2.4^\circ\text{C}$. What mass of antifreeze is required for $2\text{ L}$ of water? ($\text{K}_\text{f}\text{ water} = 1.86\ \frac{\text{K}\cdot\text{kg}}{\text{mol}}$)

The number of donor sites in dimethyl glyoxime, glycinato, diethylene triamine and EDTA are respectively

100 mL of liquid A was mixed with 25 mL of liquid B, to give non-ideal solution of A⁻B. The volume of this mixture will be

Assertion: Solubility of gases increases with increase in pressure. Reason: Dissolution of gas in liquid is exothermic.

Each of these questions contains two statements. Assertion (A) and Reason (R). Each of these questions also has four alternative choices, only one of which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) given below. Assertion (A) Osmotic pressure of 0.1 N urea solution is less than that of 0.1M NaCl solution. Reason (R) Osmotic pressure is not colligative property.

Assertion: When $1\text{M }\text{CuSO}_4$ (aq) solution is electrolysed using copper electrodes, copper is dissolved at anode and copper gets deposited at cathode. Reason: The standard oxidation potential of copper is less than the standard oxidation potential of water and standard reduction potential of copper is greater than the standard reduction potential of water.

Assertion :A non volatile solute added in solvent liquid then freezing point of mixture decreases. Reason :Vapour pressure decrease by addition of non volatile solute, so equilibrium point where Vp of solid and VP of liquid are equal can reach at lower temp.

Assertion: The normality of 0.3 M aqueous solution of H₃PO₄ is equal to 0.6 N. Reason: Equivalent weight of H₃PO₃ = \( \frac{\text{Molecular weight of H₃PO₄}}{3} \)

$3.5\text{ g}$ of a mixture of $\text{NaOH}$ and $\text{KOH}$ were dissolved and made up to $250\text{ mL}$. $25\text{ mL}$ of this solution were completely neutralised by $17\text{ mL}$ of $(\text{N}/2)\ \text{HCl}$ solution. Then, the percentage of $\text{KOH}$ in the mixture is:

We have three aqueous solutions of $\text{NaCl}$ labelled as (A), (B) and (C) with concentrations of $0.1\text{ M}$, $0.01\text{ M}$ and $0.001\text{ M}$, respectively. The value of the van 't Hoff factor ($i$) of these solutions will be in the order:

Assertion (A): Buffer solution are composed of strong acids and strong bases. Reason (R): It maintain the pH to a constant value of 7.4.

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct answer out of the following choice. Assertion (A): $\Delta H_{\text{mixing}}$ and $\Delta V_{\text{mixing}}$ for non-ideal solution with +ve deviation is zero. Reason (R): A-B interaction is more than that between A-A and B-B.

Two elements A and B form compounds of formula AB₂ and AB₄. When dissolved in 20.0 g of benzene 1.0 g of AB₂ lowers f. pt. by 2.3°C whereas 1.0 g of AB₄ lowers f. pt. by 1.3°C. The Kf for benzene is 5.1. The atomic masses of A and B are

The freezing point of a solution containing 0.2 g of acetic acid in 20.0 g benzene is lowered by 0.45°C. The degree of association of acetic acid in benzene is (Assume acetic acid dimerises in benzene and Kf for benzene = 5.12 K kg mol⁻¹) Mₒbserved of acetic acid = 113.78

Assertion: Acetone and aniline shows negative deviations. Reason: H⁻bonding between acetone and aniline is stronger than that between acetone-acetone and aniline-aniline.

100 mL of liquid A was mixed with 25 mL of liquid B, to give non-ideal solution of A⁻B. The volume of this mixture will be

Assertion (A) Osmotic pressure of 0.1 N urea solution is less than that of 0.1 M NaCl solution. Reason (R) Osmotic pressure is not a colligative property.

Which of the following aqueous solutions has the highest boiling point?

Assertion Addition of a non-volatile solute to a volatile solvent increases the boiling point. Reason Addition of non-volatile solute results in lowering of vapour pressure.

Which of the following is true for an ideal solution?

Boiling point of benzene is 353.23 K. When 1.8 g of non-volatile solute is dissolved in 90 g of benzene, then boiling point is raised to 354.11 K. Given K_b (benzene) = 2.53 kg mol⁻¹. The molecular mass of non-volatile substance is

Strength of H₂O₂ is 15.18 g L⁻¹, then it is equal to

Which is correct order of solubility in water?

Assertion: The solubility of a gas in a liquid increases with increase of pressure. Reason: The solubility of a gas in a liquid is directly proportional to the pressure of the gas.

Assertion : Helium is used in diving apparatus. Reason : Solubility of helium is less in blood.

Assertion : A non volatile solute is mixed in a solution then elevation in boiling point and depression in freezing point both are 2 K. Reason : Elevation in boiling point and depression in freezing point both depend on melting point of non-volatile solute.

100 cm³ of a given sample of H₂O₂ gives 1000 cm³ of O₂ at S.T.P. The given sample is (a) 10% H₂O₂ (b) 90% H₂O₂ (c) 10 volume H₂O₂ (d) 100 volume H₂O₂

When 25 g of Na₂SO₄ is dissolved in 10³ kg of solution, its concentration will be

Assertion: The molality of the solution does not change with change in temperature. Reason: The molality is expressed in units of moles per 1000 g of solvent.

For a dilute solution, Raoult’s law states that

A 0.1 molal solution of an acid is 4.5% ionized. Calculate freezing point. (molecular weight of the acid is 300). Kf = 1.86 K mol⁻¹ kg.

Tincture of iodine is

What is the molarity of H₂SO₄ solution that has a density of 1.84 g/cc at 35°C and contains 98% by weight?

A mixture of two miscible liquids A and B is distilled under equilibrium conditions at 1 atm pressure. The mole fraction of A in solution and vapour phase are 0.30 and 0.60 respectively. Assuming ideal behaviour of the solution and the vapour, calculate the ratio of the vapour pressure of pure A to that of pure B.

Assertion: When a concentrated solution is diluted by adding more water, molarity of the solution remains unchanged. Reason: Product of moles of a solute and volume is equal to the molarity.

1 mole each of the following compounds is dissolved in 1 L of solution. Which will have the largest ΔTₚ value?

The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non-volatile, non-electrolyte solid weighing 0.5 g is added to 39.0 g of benzene (molar mass 78 g/mol). The vapour pressure of the solution then is 0.845 bar. What is the molecular mass of the solid substance?