Chemistry | Solid State [Class – 12]
Very Important Examination Questions & Answers For Practice
Note – All questions are very important examination coming theoretical questions
with answers for exams practice
1. How is it that alcohol (ethoxyethane) and water are miscible in all
proportions ?
Answer: (i) Both are polar and hence miscible.
(ii) They form hydrogen bonds with each other. This further increase their
mcibility.
2. What is the relation between normality and molarity of a given solution of
H2SO4 ?
Answer: Normality = 2 x Molarity.
3. What is the sum of mole fractions of all the components in a three
component system ?
Answer: x1 + x2 + x3 = 1.
4. Why does the molality of a solution remain unchanged with temperature ?
Answer: Molality of a solution involves masses of the solute and solvent which
do not change with tempertature.
, 5. Calculate the molality of H2SO4 if the density of 10% (w/w) aqueous solution
of H2SO4 is 1.84 g cm-3 (Molar mass of H2SO4 = 98 g mol-1).
Answer: 10% (w/w) H2SO4 solution means 10 g H2SO4 are present in 100g of
solution, i.e., water present = 90 g
𝟏𝟎
𝟗𝟖
Molality = × 𝟏𝟎𝟎𝟎 = 1.13 m
𝟗𝟎
6. Define azeotropic mixture.
Answer: This type of liquid mixture, having a definite composition, and boiling
like a pure liquid, is called a constant boiling mixture or an azeotropic mixture or
also known as azeotrope.
7. Write the mathematical form of Raoult’s law of relative lowering of vapour
pressure.
𝒑°−𝒑𝒔 𝒏𝟐
Answer: =
𝒑° 𝒏𝟏 +𝒏𝟐
8. What are isotonic solutions ? Give one example.
Answer: Solutions having equal osmotic pressure are called isotonic solutions,
e.g., 0.1 M glucose and 0.1 M sucrose solutions.
9. Define reverse osmosis. Give one use of it.
Answer: In osmosis, net flow of solvent across the semipermeable membrane is
from solvent to solution. The flow can be reversed by applying pressure greater
than osmotic pressure on the solution. This is called reverse osmosis. It is used
for desalination of sea water.
Very Important Examination Questions & Answers For Practice
Note – All questions are very important examination coming theoretical questions
with answers for exams practice
1. How is it that alcohol (ethoxyethane) and water are miscible in all
proportions ?
Answer: (i) Both are polar and hence miscible.
(ii) They form hydrogen bonds with each other. This further increase their
mcibility.
2. What is the relation between normality and molarity of a given solution of
H2SO4 ?
Answer: Normality = 2 x Molarity.
3. What is the sum of mole fractions of all the components in a three
component system ?
Answer: x1 + x2 + x3 = 1.
4. Why does the molality of a solution remain unchanged with temperature ?
Answer: Molality of a solution involves masses of the solute and solvent which
do not change with tempertature.
, 5. Calculate the molality of H2SO4 if the density of 10% (w/w) aqueous solution
of H2SO4 is 1.84 g cm-3 (Molar mass of H2SO4 = 98 g mol-1).
Answer: 10% (w/w) H2SO4 solution means 10 g H2SO4 are present in 100g of
solution, i.e., water present = 90 g
𝟏𝟎
𝟗𝟖
Molality = × 𝟏𝟎𝟎𝟎 = 1.13 m
𝟗𝟎
6. Define azeotropic mixture.
Answer: This type of liquid mixture, having a definite composition, and boiling
like a pure liquid, is called a constant boiling mixture or an azeotropic mixture or
also known as azeotrope.
7. Write the mathematical form of Raoult’s law of relative lowering of vapour
pressure.
𝒑°−𝒑𝒔 𝒏𝟐
Answer: =
𝒑° 𝒏𝟏 +𝒏𝟐
8. What are isotonic solutions ? Give one example.
Answer: Solutions having equal osmotic pressure are called isotonic solutions,
e.g., 0.1 M glucose and 0.1 M sucrose solutions.
9. Define reverse osmosis. Give one use of it.
Answer: In osmosis, net flow of solvent across the semipermeable membrane is
from solvent to solution. The flow can be reversed by applying pressure greater
than osmotic pressure on the solution. This is called reverse osmosis. It is used
for desalination of sea water.
