Solution

Class 12th Chemistry – 2 SOLUTION MCQs

"Formality" is an expression used for:

Correct! Wrong!

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Ionic solids do not exist as independent molecules but as a 3 dimensional crystalline lattice. Concentration is therefore expressed in formality: the number of formula units of ionic solid present per litre of solution.

The osmotic pressure of dilute solution is____

Correct! Wrong!

Osmotic pressure (∏) = CRT {C = concentration in molarity, R= gas constant (0.0821 L atm /kmol), T= temperature in Kelvin} Hence, osmotic pressure is directly proportional to concentration.

There are two solutions, A & B of 25% by mass each, whose densities are 2.80 gm cm-3 and 1.02gm cm-3 respectively. The molarity of A & B is in the ratio (given mol.mass of A = 60, mol.mass of B = 46 ).

Correct! Wrong!

Molarity of A = 25 x 2.8 x10/ 60 = 11.6 (formula for calculation of molarity = %age x density x 1000/molar mass) Molarity of B = 25 x 1.02 x 10/46= 5.5 Hence, the ratio is A : B is 2:1.

The Vant Hoff 's factor for a dilute solution of NaHSO4 is likely to be ;

Correct! Wrong!

First NaHSO4 dissociates into Na +ion and HSO4--. Then in the second phase HSO4-- dissociates into H+ and SO42-- ions so total no of particles are 3.

Hydrogen in presence of finely divided Palladium is used for hydrogenation of alkenes. Hydrogen forms what type of solution with Palladium?

Correct! Wrong!

It is a solid solution with hydrogen gas as the solute and solid palladium as the solvent.

Hydrated salts can be classified as ____ solutions.

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Hydrated salts are termed as liquid in solid solutions because the water molucules are trapped between the spaces or voids of the salt molecules and are bound by chemical bonds. For e.g., in copper sulphate 5 molecules of water are associated, in magnesium sulphate 7 molecules are associated. The water trapped in the molecule of a salt make it classified as hydrated salts.

Binary solutions are made of:

Correct! Wrong!

Binary solutions consist of only two components. One solute and a solvent. The solvent is the media for dissolution and the solute is the substance weighed and dissolved.

What would be the molarity of 20 cm-3 of urine containing 15 milligrams of urea ? ( Molar mass of urea is 60) is;

Correct! Wrong!

No. of moles of urea = mass /molar mass 0.015 gm/60 = 2.5 x 10-4moles , Molarity = moles/volume in litres 2.5 x 10-4 x1000/ 20 = 0.0125M

Molar mass of polymers or macromolecules are best determined by____

Correct! Wrong!

Molar mass of polymers or macromolecules are best determined by Osmotic pressure method. Osmotic pressure method is preferred because it is sensitive and can be carried out at room temperature without disruption of the structure of the polymer or macromolecule. Small change in osmotic pressure can be measured with accuracy. Other methods do have an impact on the structure. They may disintegrate and the molar mass calculated may not be correct due to temperature variation.

Henry's law is not applicable in dissolution of:

Correct! Wrong!

Henry's law gives a quantitative relation between pressure and solubility of a gas in the solvent. Hydrogen, carbon dioxide, ammonia are soluble whereas due to non polarity nature of methane, it is insoluble in water.

Rat poison has a higher concentration of which solution?

Correct! Wrong!

Rat poison has a high concentration of sodium fluoride.

Henry's constant KH value of H2, N2 and He in water at 293K are 69.16 bar, 76.48 bar and 144.97 bar. The solubility of the gas in water is then in the order of:

Correct! Wrong!

P = KH .x mole fraction of the gas, Greater the KH value, lower the solubility of the gas. Hence, option A is correct.

Amalgam is termed as a:

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An amalgam is a solution of liquid solute in solid solvent.

The pressure at which liquid and vapour can co-exist at equilibrium is termed as ____.

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Saturated vapour pressure is that pressure at which the vapour pressure of the liquid becomes constant. There is no further change how much ever more pressure is applied. When the vapours reach saturation, vapours and liquid co-exist.

The Vant Hoff 's factor for a dilute solution of NaHSO4 is likely to be ;

Correct! Wrong!

First NaHSO4 dissociates into Na +ion and HSO4--. Then in the second phase HSO4-- dissociates into H+ and SO42-- ions so total no of particles are 3.

Solubility of a solid in liquid is defined as ____.

Correct! Wrong!

Solubility of a solid in liquid is defined as the maximum amount of the substance dissolved in 100 g of water.

In Ionic compounds solubility increases with increase of temperature because ____.

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The process of dissolution of ionic compound is endothermic because energy is required to break the lattice against the strong inter ionic forces between the ions.

The solubility curve is a ____.

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The solubility curve is a continuous solubility curve Vs temperature.

Iodine is more soluble in alcohol than water because ____.

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Iodine is covalent in nature because of its electronic configuration. The one odd electron of each atom in p- orbital overlap forming a covalent bond between the two atoms. Being covalent, it is non polar also. Hence, Iodine is more soluble in alcohol than water.

Ethanol-Water mixture shows positive deviations from Raoult's law. The vapour pressure of this solution:

Correct! Wrong!

For positive deviations the magnitude of A-B interactions is lower than the magnitude of A-A and B-B interactions. Thus the molecules of A and B find it easier to escape to vapour phase resulting in higher vapour pressure.

Non polar compounds dissolve in non polar solvents because of similar ____.

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The interaction of solute-solute, solvent-solvent and solute-solvent should be equal for uniform dissolution to take place.

20 ml of 1N HNO3, 75 ml of N/5 H2SO4 and 15 ml of N/3 HCl are mixed and the volume is made to one litre. The normality of the resulting solution is:

Correct! Wrong!

N1V1 + N2V2 + N3V3 = N4V4 , 20 x N + N/5 x 75 + 15 x N/3 = N x 1000, 20 + 15 +5 = N4 x 1000, N4 = 0.04 or N/25

An ideal solution shows a linear variation for Raoult's law when vapour pressure is plotted against:

Correct! Wrong!

If a solution obey's Raoult's law its vapour pressure varies linearly with concentration expressed in mole fraction.

Which of the following concentration terms expressed, would change with increase in temperature?

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Option A, C and D are mass dependent and molarity is volume dependent.

Solutions are made by dissolving one mole of glucose, urea and common salt. Equal osmotic pressure will be produced by solutions of____

Correct! Wrong!

Urea and glucose will produce equal osmotic pressure. It will not dissociate and will remain as one mole. But in case of other three options, sodium chloride will dissociate giving two particles; Hence, will not have same osmotic pressure. There will be increase in the osmotic pressure. Hence the first option is correct.

10g of sugar is dissolved in 90g of water resulting in 100g of solution. The concentration of sugar in the solution is

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Mass % (w/w) is defined as Mass of the component/total mass of the solution X 100

Which of the following compounds is termed as antifreeze ____

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Ethylene glycol forms a miscible solution and acts as anti freeze, by lowering the freezing point of water. Ethanol and isopropyl alcohol have very low vapour pressure. Hence, they would evaporate faster. They are not used as antifreeze. Glycerol has high viscosity. So, it is not used with water.

Which of the following phenomenon applied in desalination of plant to remove salt from sea water. Water is squeezed out from sea water.

Correct! Wrong!

The flow of water is from the solution to the solvent. This is achieved when a pressure larger than the osmotic pressure is applied to the solution side. This is the phenomenon applied in desalination plant to remove salt from sea water. Water is squeezed out from sea water.

0 .785 gms of oxalic acid (molecular mass 126) dissolved in 250 ml is titrated against 0.01 M KMnO4. The volume of KMnO4 used to neutralise 20ml. of oxalic acid solution is:

Correct! Wrong!

Molarity of Oxalic acid = 0.785/126 x 1000/250 = 0.024, M1V1n2 = M2V2n1, 0.024 x 2 x 20 = 0.01 x 5 x V2, V2 = 19.2 ml. (5 moles of oxalic acid neutralises 2 moles of KMnO4 in a balanced equation. Hence, n1 = 5 & n2 = 2.)

The ionic concentration of solutions used for intravenous injection should be:

Correct! Wrong!

The solutions inside and outside the blood vessel should be of same concentration so that the osmotic pressure is the same. The solutions are then said to be isotonic. Hence, the injected solution from the injection has to be of the same concentration of blood.

Class 12th Chemistry - 2 SOLUTION MCQs
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Class 12th Chemistry - 2 SOLUTION MCQs