AIIMS Chemistry Solutions Class 12 Questions

Higher the hydration energy of a compound, higher will be its solubility. Be²⁺ has highest hydration energy, therefore, its solubility is maximum.

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 CHCl₃ and CH₂Cl₂ are 200 and 41.5 atm respectively. The weight of CHCl₃ and CH₂Cl₂ are respectively 11.9 g and 17 gm. The molar mass of CHCl₃ is 119.5 g/mol and the molar mass of CH₂Cl₂ is 85 g/mol. The number of moles of CHCl₃ is calculated below.

The mole fraction of solute is equal to the relative lowering of vapour pressure, x₂ = (P₀ - Pₛ) / P₀. Substitute the given values in the above equation.

63% w/w HNO₃ solution. Calculate the volume of solution containing 63 g of HNO₃ in 100g of solution.

In isolated system, find the condition for spontaneous reaction.

When applied pressure is more than osmotic pressure, then water molecules move from lower concentration to higher concentration of water through semi-permeable membrane and this process is called reverse osmosis and it is used for desalination of water.

The solutions which obey Raoult's law over the entire range of concentration and at all temperatures are called ideal solution. For ideal solution, enthalpy of mixing of pure components to form the solution is zero and the volume of mixing is also zero.

The blue color of the solution is due to the excitation of electrons. Alkali metals are dissolved in liquid ammonia and give blue colored solution. The high conductivity of such solutions is due to the presence of ammoniated electron. The reaction is shown below. M + (x + y)NH₃ → [M(NH₃)ₓ]⁺[e(NH₃)ᵧ]⁻

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).

The expression for Vont Hoff factor, i, is, i = ΔT_f / K_f m

The osmotic pressure can be calculated as:

Ethyleneglycol is used as antifreeze to reduce freezing point of water to −2.4°C. What mass of antifreeze is required for 2L water? (Kf water = 1.86 K·kg/mole)

Henry’s law states that at increasing the pressure at constant temperature, there is increase in the solubility of gas in liquid occurs.

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.

It is true that if one solvent mixed with other solvent, then vapour pressure of one increases and other decreases. Also, if a solute added into solvent, then vapour pressure of solvent decreases. But these statements are not related to each other. So, both assertion and reason are true but reason is not the correct explanation of assertion.

The assertion and reason both are correct and both are related to each other as, in case of liquid and solid vapor pressure is equal at freezing point. And the vapour pressure decreases if the solute is added to the mixture.

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 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?

Tincture iodine is

A 5% solution (by mass) of cane sugar in water has freezing point of 271 K and freezing point of pure water is 273.15 K. The freezing point of a 5% solution (by mass) of glucose in water is