Chemistry M.C.Q [1M]

1. Saturated

Explanation:

The maximum number of moles of solute that can be dissolved in a given volume of solution represents the solubility of solution.

A solution with the maximum possible amount of solute is saturated.

Hence a saturated solution must be prepared to determine the solubility of a solute in water,

2. Positive deviation from Raoult’s Law.

1. Increases with increase in temperature.

Explanation:

Value of Henry’s constant increases with increase in temperature.

4. 0.016

Explanation:

Apply the relation, M₁V₁ = M₂V₂

Given, M₁ = 0.02M, V₁ = 4L, M₂ = ?, V₂ = 5L

Therefore, 0.02 × 4L = M₂ × 5L

 M₂ = 0.08/5

=0.016M

2. 87%

2. 0.1M urea sol

2. Heat of dissolution

Explanation:

The heat of solution or mixing has a negative side. Dissolution’s heat.

2. 32.05

3. Pressure.

Explanation:

Solubility of a solid in liquid does not depend upon pressure since solid and liquids are almost incompressible.

2. Increases to a constant value.

1. Two different solutions of sucrose of same molality prepared in different solvents will have the same depression in freezing point.

Explanation:

Tf = Kfm Since Kf values depend upon the nature of solvent, the depression in freezing point of the solution would not be the same.

1. vapour pressure in container (A) is more than that in container (B).

Explanation:

Since NaCl is a non-volatile solute, it will reduce vapour pressure of the solution. Hence, vapour pressure of pure water in container A is more than in container B.

4. All of the above

Explanation:

The rate of vapourization of water depends on the temperature and surface area. 

The kinetic energy of molecules depends on the temperature of the water.

Increasing temperature or surface area increases the rate of evaporation and vice-versa.

2. Vapour pressure only depends on temperature and not on the nature of substance.

Explanation:

The vapour pressure depends on the temperature and the nature of substance.

1. At specific composition methanol-acetone mixture will form minimum boiling azeotrope and will show positive deviation from Raoult’s law.

Explanation:

At specific composition methanol-acetone mixture will show positive deviation from Raoulfs law as it has lesser interactions than methanol- methanol and acetone-acetone interactions. Hence it forms minimum boiling azeotrope.

1. Solid in gas solution

Explanation:

Solid in gaseous solution is an example of camphor in N2 gas. Gaseous solution refers to a solution in which the solvent is gaseous. Other gaseous solutions include air (O2 + N2), iodine vapors in air, humidity in air, and so on.

3. FeCl₃​, 30% ionised

Explanation:

Soluten a i = [1 + (n -1)a]

KCl 20.51.5

K₂​SO_4​ 30.41.8 

FeCl₃​ 40.31.9

SnCl₄​ 50.21.8

1. A non volatile solid is dissolved in a volatile liquid.
2. A non volatile liquid is dissolved in another volatile liquid.

Explanation:

Colligative properties are observed when a non-volatile solid or liquid are dissolved in a volatile liquid.

3. These will form minimum boiling azeotrope.
4. These will not form ideal solution.

Explanation:

In a mixture of benzene and toluene intermolecular forces between benzene and toluene molecules would be nearly of the same strength as those of two benzene molecules and two toluene molecules separately. The solution will, therefore, form an ideal solution & obey Raoult’s law. So, the option (iii) & (iv) is not true.

2. Osmotic pressure is same.
3. Solute and solvent may or may not be same.

Explanation:

For isotonic solutions osmotic pressure is same, solute or solvent may not be same.

3. The van't Hoff factor

Explanation:

The van't Hoff factor is the ratio of the actual value of a colligative property to the value calculated. It is assumed that the substance is a nonelectroyte.

It can also be represented as the ratio of actual number of particles to the number of particles for no ionization.

4. Potassium dichromate

Explanation:

The primary standard is a compound of  sufficient purity from which standard solutions of known normalities can be prepared by direct weighing of it and diluting to a defined volume of solution.

Potassium Dichromate(K₂​Cr₂​O₇​) is suitable to be used as a primary standard. It cannot be obtained in very pure form. It readily reacts with any traces of organic material or any other reducing substance in wate

4. Powdered sugar in hot water.

Explanation:

Since the solution is cool to touch, the dissolution is endothermic. Therefore, high temperature will favour dissolution. Further, powdered sugar has large surface area and is favourable for dissolution.

4. HCI

Explanation:

The following substances were all dissolved in 100 grams of water at 290K to produce saturated solutions. If the solution is heated to 310K, HCl will have a decrease in its solubility. HCl is a gas. The solubility of a gas in a solution is inversely proportional to the absolute temperature. With increase in the temperature, the solubility of a gas decreases.

4. Dissolving salt in the water

Explanation:

Vapour pressure is a surface phenomenon, when the surface area is more, vapour pressure will be more. When we add solute, what we do is we decrease the vapour pressure of solvent because same of the salt ions will be present at the solvent surface, thus taking place of same of the solvent particles which were actively participating in maintain, that previous high value of vapour pressure. So, the equilibrium vapour pressure value decreases. Thus, dissolving salt in water results in decreasing of equilibrium vapour pressure.

2. Water will move from side (B) to side (A) if a pressure greater than osmotic pressure is applied on piston (B).

Explanation:

Water will move from side (B) to side (A) if pressure greater than osmotic pressure is applied on piston (B) due to reverse osmosis.

1. Mole fraction.

Explanation:

It is mole fraction (x) which is useful in relating concentration of solution with its vapour pressure. For example according to Rault's law in a binary solution of two volatile liquids, p₁ = x₁ p⁰₁ where p₁ is vapour pressure of component 1, and x₁ is its mole fraction in solution, p⁰₁ denotes the vapour pressure of pure solvent.

3. Equal to the rate of crytallisation

Explanation:

Crystallization is the process of the formation of solid crystals precipitating from a solution.

In an unsaturated solution, the rate of dissolution of a solute in a volatile liquid solvent is greater than the rate of crystallization. 

In a supersaturated solution, the rate of dissolution of a solute in a volatile liquid solvent is less than the rate of crystallization.

At equilibrium, the rate of dissolution of a solute in a volatile liquid solvent is equal to the rate of crystallization.

4. The solute precipitates out of the solution.

Explanation:

Solute particles leave the solution and form a crystalline precipitate when a solute crystal is added to a supersaturated solution. Seeding refers to the addition of the solute crystal.

1. Solute and solvent

Explanation:

The solution is made up of two components that is solute and solvent.

2. Same as what would be if the glass plate were removed

Explanation:

The vapour pressure of the liquid in the vessel is same as what would be if the glass plate were removed. Vapour pressure is characteristic property of a solvent at a temperature.

1. Greater than one and less than one

Explanation:

In case of association of solute particles in solution, the observed molecular weight of solute being more than the normal, the value of factor 'i' is less than unity (i.e. i < 1), while for dissociation the value of i is greater than unity (i.e. i > 1), because the observed molecular weight has lesser value than normal molecular weight.

2. 50

2. Toluene and Benzene

Explanation:

Toluene and Benzene are very similar molecules  and hence are ideal solution,  others are solutions showing positive deviation (Theory based. To be memorized.) 

2. First increases and then remains constant

Explanation:

The molecules of a gas are in a state of random motion. They continuously collide against the walls of the container. Even at ordinary temperature and pressure, the number of molecular collisions with walls is very large. During each collision, certain momentum is transferred to the walls of the container. The pressure exerted by the gas is due to continuous bombardment of gas molecules against the walls of the container. Due to this continuous bombardment, the walls of the container experience a continuous force which is equal to the total momentum imparted to the walls per second. The average force experienced per unit area of the walls of the container determines the pressure exerted by the gas. This should be clear from the fact that although the molecule collisions are random, the pressure remains constant.

3. Liquid A has lower latent heat of vaporisation than that of liquid B

Explanation:

Liquid A gives cooling sensation means liquid A is absorbing more heat from the skin, so, liquid A and B can be differentiated as liquid A has lower latent heat of vaporisation than that of liquid B.

1. It depends on the concentration of a non electrolyte solute in solution and does not depend on the nature of the solute molecules.
2. It depends on number of particles of electrolyte solute in solution and does not depend on the nature of the solute particles.

Explanation:

Relative lowering of vapour pressure depends on concentration of non-electrolyte solute in solution and number of particles of electrolyte solute. It does not depend on nature of solute in both conditions.

4. A–B interactions are weaker than those between A–A or B–B.

Explanation:

1. The solutions which show large positive deviation from Rault's law form minimum boiling azeotrope at some specific composition.
2. In case of positive deviation from Rault's law A-B interactions are weaker than those between A–A or B–B.

3. i_A = i_B = i_C

Explanation:

The value of van’t Hoff’s factor will be i_A= i_B = i_C due to complete dissociation of strong electrolyte (NaCl) in dilute solutions. On complete dissociation value of i for NaCl is 2.

1. Ideal

Explanation:

Due to absence of polarity, benzene and toluene dont have any interaction forces so they dont show any deviation and forms ideal solutions.

3. Ar < CO₂ < CH₄ < HCHO

Explanation:

Ar < CO₂ < CH₄ < HCHO Explanation: Higher the value of K_H lower will be the solubility of the gas at a given pressure, hence the solubility of given gases would increase with increase in K_H values.

4. 0.1M Ba(NO₃​)_2​ and 0.1M Na₂​SO₄

Explanation:

Isotonic solutions have the same osmotic pressure and same molar concentration.

The solution of 0.1M Ba(NO₃​)₂​ and 0.1M Na₂​SO₄​ are isotonic.

The osmotic pressure of 0.1M Ba(NO_3​)₂​

= iMRT = 3 × 0.1RT = 0.3RT

Osmotic pressure of 0.1M Na₂​SO_4​

= iMRT = 3 × 0.1RT = 0.3RT

The correct answer is "The solution of 0.1M Ba(NO₃​)₂​ and 0.1M Na₂​SO₄​ are isotonic".

4. Lonisation of solute should occurs to a small extent

Explanation:

In an ideal solution, no change in volume on mixing, no change in enthalpy on mixing and it obeys Raoults law but ionisation of solute should not occur to a small extent.