Answer :
1. Answer : (d) ppm
Explanation: Since the amount of pollutants present in the atmosphere is very small, atmospheric pollution is measured in parts per million (ppm).
2.Answer : (b) 0.5
Explanation: Weight of water in sugar syrup
= 234.2 − 34.2
= 200gm
Molecular weight of sugar = 342
Molal concentration \(=\frac{34.2}{342}\times\frac{1000}{200}\)
Molal concentration = 0.5
3. Answer : (b) sum of the numbers of electrons and protons of an atom
Explanation: The atomic mass of an atom is an empirically measured property, which is equivalent to the sum mass of protons, neutrons, and electrons that make up the atom (with a small adjustment for nuclear binding energy).
4. Answer : (b) Henry’s law
Explanation: Henry's Law is the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid.
5. Answer : (d) mercury
Explanation: Mercury exerts the lower vapour pressure because of the strong bond among its atom.
6. Answer : (b) Raoult’s law
Explanation: The relationship is known as the Raoult's law which states that for a solution of volatile liquids, the partial vapour pressure of each component of the solution is directly proportional to its mole fraction present in solution.
7. Answer : (b) Acetone + Ethanol
Explanation: Acetone + ethanol is an example of solutions showing positive deviation from Raoult's law.
8. Answer : (a) Acetone-chloroform
Explanation: acetone – chloroform is a non-ideal solution and has a negative deviation. It is a maximum boiling azeotrope.
9. Answer : (b) hypertonic solution
Explanation: Hypertonic solution has high osmotic pressure. When a plant cell is placed in hypertonic solution water will diffuse out of the cell resulting in shrinking of the cell.
10.Answer : (c) solute molecules to the total number of molecules in solution
Explanation: Relative lowering of vapour pressure. The vapour pressure of a liquid is the pressure of the vapour which is in equilibrium with that liquid. The vapour pressure of a solvent is lowered when a non-volatile solute is dissolved in it to form a solution.
11. Answer : (b) increasing the number of solute molecules
Explanation: The osmotic pressure of a solution increases as the number of solute molecules increases. Excess pressure produced on the solution side owing to osmosis is known as osmotic pressure. The osmotic pressure of a solution increases as the number of solute molecules increases.
12. Answer : (b) depression in freezing point of snow
Explanation: When salt is spread over snow covered roads, snow starts melting from the surface because depression of freezing point of water takes place due to addition of salt. It helps in clearing of roads. Hence, the phenomena is depression in freezing point which helps in clearing the snow covered roads in hilly areas.
13.Answer : (c) cellulose acetate
Explanation: Cellulose acetate, potassium ferrocyanide, etc. are used as semipermeable membrane for carrying out reverse osmosis.
14. Answer : (b) 87%
Explanation: \(Mg(NO_3)_2\longrightarrow\) \(Mg^{2+}+2NO^-_3\)
\(\alpha=\frac{i-1}{n-1}\)
\(=\frac{2.74-1}{3-1}\)
\(=\frac{1.74}{2}\)
= 0.87
Degree of Dissociation
= 0.87(100)
= 87%
15. Answer : (a) Mole fraction
Explanation: Mole fraction is useful in relating vapour pressure with concentration of solution. According to Raoult's law, the partial vapour pressure of each component in the solution is directly proportional to its mole fraction.
16. Answer : (c) equal to the rate of crystallisation
Explanation: This means that the rate of crystallisation is equal to the rate of the dissolution for a solid solute in a volatile liquid. At equilibrium the rate of dissolution will be equal to the rate of crystallisation.
17. Answer : (d) unchanged
Explanation: If the molality of a dilute solution is doubled, the value of the molal depression constant (Kf) remains unchanged. Because molal depression is constantly dependent on the nature of the solvent, not on solute.
18. Answer : (b) Molarity
Explanation: molarity is the concentration term which is temperature dependent.
19. Answer : (d) Addition of water
Explanation: However, the addition of solvent, ie, dilution increases the surface area of the liquid surface, thus results in increased vapour pressure. Hence, the addition of water to the aqueous solution of (1 molal) KI, result in increased vapour pressure.
20. Answer : (b) Shows a positive deviation from Raoult's law
Explanation: A solution of acetone in ethanol shows a positive deviation from Raoult's law due to miscibility of these two liquids with a difference of polarity and length of the hydrocarbon chain.
21. Answer : (b) Water + Nitric acid
Explanation: The mixture that forms maximum boiling azeotrope is water and nitric acid. This mixture of water and nitric acid shows negative deviation from Roult's law and it will form maximum boiling azeotrope.
22. Answer : (c) Osmotic pressure
Explanation: An isotonic solution is a solution that has the same osmolarity or solute concentration as another solution.
23. Answer : (a) Potassium Sulphate
Explanation: Urea and glucose do not dissociate in solution. Sodium chloride gives two ions and potassium sulphate gives three ions per formula unit. Therefore, the effective number of particles is maximum in potassium sulphate. Hence, its freezing point is lowest.
24. Answer : (c) Emulsion
Explanation: An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids.
25. Answer : (d) 3
Explanation: Ba(OH)2 is a strong electrolyte, so its 100% dissociation occurs in solution.
Van't off factor(i) = Total number of ions present in the solution.
\(Ba(OH)_2\longrightarrow \) \(Ba^{2+}+2OH^-\)
So, the total number of ions in the solution is 3.
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