Solutions(11th And 12th > Chemistry) Questions and answers for exam Preparation

11th And 12th > Chemistry

SOLUTIONS MCQs

Total Questions : 30

Page 1 of 2 pages

Question 1. Which of the followings is correct –

For an non-ideal solution △Hmix > 0, △Vmix > 0.
In a solution showing negative deviation from Raoult's law A-B type of molecular interactions are stronger than A-A and B-B type of molecular interactions.
Nitric acid and Water solution shows positive deviation from Raoult's law.
Azeotrope boils at temperature below the boiling temperature of its constituents.

Answer: Option B
: B

a) △ H_{m i x} > 0, △ V m i x > 0

aretrueformixturesshowing positivedeviations from Raoult'slaw only.Hence option (a)isincorrect

b) It is true c) Nitric acid and water forms intermolecular H-bonding. Hence shows Negative deviation from Raoult's law. d) Azeotropes are of two types – minimum and maximum boiling azeotropes. Only minimum boiling Azeotrope boils at temperature below the boiling temperature of its constituents. Hence option (d) is incorrect.

Question 2. Aquatic species feel more comfortable in winter than in summer because -

% of O2 in air decreases in summer due to high temperature
Atmospheric pressure decreases in summer leading to reduced solubility of gases in water
Solubility of gases in water decreases as the temperature increases due to increased Henry’s constant
Aquatic species feel skin burn due to increased temperature of the water.

Answer: Option C
: C

According Henry’slaw ofsolubilityofgases -

P = K_{H} X

Withincreasein temperatureincreases,thus ‘x’ decreases given thepartialpressureof

O_{2}

remainssame.

Question 3. In an experiment on depression of freezing point, two beakers leveled as A and B were filled with 1000 g. of water each. 40 g and 80 g of a certain non-electrolytic solute were added to both the beakers and freezing point of the solutions were noted as

T_{f A}

and

T_{f B}

respectively. Now both the solutions were poured into an empty beaker C and the freezing point of the mixed solution is found to be

T_{f C}

. What is the ratio

T_{f A} : T_{f B} : T_{f C} ?

1 : 2 : 3
2 : 4 : 3
2 : 4 : 8
1 : 4 : 8

Answer: Option B
: B

△ T_{f} = K_{f} m

\Rightarrow 0 - T_{f} = K_{f} m

\Rightarrow= - K_{f} m

If 40 g of solute contains 'x'~moles of it then 80 g of the solut ill contains '2x' molesofit

m_{A} = \frac{x}{\frac{W t . o f s o l v e n t i n g}{1000}} = \frac{x}{\frac{1000}{1000}} = x

m_{B} = \frac{2 x}{\frac{W t . o f s o l v e n t i n g}{1000}} = \frac{x}{\frac{1000}{1000}} = 2 x

m_{C} = \frac{3 x}{\frac{W t . o f s o l v e n t i n g}{1000}} = \frac{3 x}{\frac{1000}{1000}} = 1.5 x

Required ration

T_{f A} : T_{f B} : T_{f c} = 1.2 : 1.5 = 2 : 4 : 3

Question 4. Which of the following solutions in water will have the lowest vapour pressure

0.1 M,NaCl
0.1 M Na3 PO4
0.1 M, BaCl2
0.1 M, sucrose

Answer: Option B
: B

Depression in vapor pressure is a colligative property. More the no. of particles present in the solution lower will be the vapor pressure. consists of maximum ions hence it show lowest vapour pressure.

\begin{matrix} M o l e c u l e & N a C l & N a_{3} P o_{4} & B a C l_{2} & S u c r o s e N o . o f i o n s p e r m o l e c u l e & 1 + 1 = 2 & 3 + 1 = 4 & 1 + 2 = 3 & 1 \end{matrix}

Question 5. A solution containing 30 gms of non-volatile solute in exactly 90 gm water has a vapour pressure of 21.85 mm Hg at 250C. Further 18 gms of water is then added to the solution. The resulting solution has a vapour pressure of 22.15 mm Hg at 250C. Calculate the molecular weight of the solute.

74.2
75.6
67.83
78.7

Answer: Option C
: C

A Solution Containing 30 Gms Of Non-volatile Solute In Exact....

Question 6. A solution has a 1:4 mole ratio of pentane to hexane. The vapour pressure of the pure hydrocarbons at

20^{\circ}

is 440 mmHg for pentane and 120 mmHg for hexane. The mole fraction of pentane in the vapour phase would be

0.549
0.200
0.786
0.478

Answer: Option D
: D

Mole fractionof pentane invapourphase =

Y_{1} = \frac{P_{1}}{P_{1} + P_{2}} = \frac{P_{1}^{0} X_{1}}{P_{1}^{0} X_{1} + P_{2}^{0} X_{2}}

= \frac{440 \times \frac{1}{5}}{440 \times \frac{1}{5} + 120 \times \frac{1}{5}} = 0.478

Question 7. Which of the following liquid pairs shows a positive deviation from Raoult's law

Water-nitric acid
Benzene-methanol
Water-hydrochloric acid
Acetone-chloroform

Answer: Option B
: B

(a) Water-Nitric acid solution shows negative deviation from Raoult's law due to hydrogen bonding
(b) Benzene-methonol solution shows positive deviation due to formation hydrogen bonding
(c) Water-HCl solution shows negative deviation due to formation of hydrogen bonding
(d) Acetone-Chloroform solutions shows negative deviation due to formation of hydrogen bonding
it is prudent to remember some of these examples of solutions showing positive and negative deviations from Rault's law along with examples of ideal solutions

\begin{matrix} N e g a t i v e d e v i a t i o n f r o m R a u l t^{'} s l a w & P o s i t i v e d e v i a t i o n f r o m R a u l t^{'} s l a w & i d e a l s o l u t i o n s ∙ C h l o r o f o r m - A c e t o n e ∙ W a t e r - N i t r i c a c i d ∙ W a t e r - H C l ∙ P h e n o l - A n i l i n e & ∙ B e n z e n e - M e t h y l a l c o h o l ∙ c a r b o n d i s u l f i e - A c e t o n e ∙ C h l o r o f o r m - e t h a n o l ∙ W a t e r - E t h y l a l c o h o l & ∙ B e n z e n e - T o l u e n e ∙ n - h e x a n e^{-} n - h e p t a n e ∙ E t h y l b r o m i d e - E t h y l i o d i d e ∙ C h l o r o B e n z e n e - b r o m o B e n z e n e \end{matrix}

Question 8. Assertion (A): Molality of solution does not change with change in temperature.

Reason (R): Molality is defined as no. of moles of solute per kg of solvent. Which of the following is correct?

Both A and R are true and R is correct explanation of A
Both A and R are true and R is not a correct explanation of A
A is true but R is false.
A is false but R is true.

Answer: Option B
: B

Molalitydoesnotchange with change in temperature, because it is defined as

\frac{n o . o f . m o l e s o f s o l u t e}{w t . o f s o l v e n t i n k g}

. Neither no. of moles nor the wt. of solvent is changing with change in temperature. Hence (b) is the correct option.

Question 9. Ratio of Henry’s constant,

K_{H}

of two inert gases A

&

B is 2 at a given temperature. A mixture containing 4 moles of gas A and 8 moles of gas B is bubbled through water covered from top and solution is allowed to attain equilibrium. Assuming the absence of any other gases, what will be the ratio of mole fractions of gases in the solution.

1:1
8:9
7:8
1:2

Answer: Option B
: B

Let ‘a’ and ‘b’ moles of gases dissolve in water while rest accumulates over the solution to create partial pressure.

From Henry’s Law –

p = K_{H} X

\Rightarrow \frac{p_{1}}{P_{2}} = \frac{K_{H 1}}{K_{H 2}} \times \frac{X_{1}}{X_{2}}

\Rightarrow \frac{4 - a}{8 - b} = \frac{1}{2} \times \frac{a}{b}

\Rightarrow \frac{4 - a / b}{8 - 1} = \frac{1}{2} \times \frac{a}{b}

\Rightarrow \frac{a}{b} = \frac{4 \times 2}{9} = \frac{8}{9}

Hence Answer is option (b)

Question 10. A solution of

(A l_{2} (S O_{4})_{3})

contain 22% salt by weight and density of solution is 1.253.The molarity, normality and molality of the solution is

0.806 M, 4.83 N, 0.825 m
0.825 M, 48.3 N, 0.805 m
4.83 M, 4.83 N, 4.83 m
None

Answer: Option A
: A

Molecular wt. of

A l_{2} (S O_{4})_{3} = 2 \times 27 + 3 \times (32 + 4 \times 16) = 342 g / m o l e

Equivalent wt. of

A l_{2} (S O_{4})_{3} = E q . w t . o f A l^{3 +} + E q . W t o f S O_{4}^{2 -} = \frac{27}{3} + \frac{96}{2}

= 57 g e q

No. of. equivalent per mole

= \frac{342}{57} = 6

Let volume of solutions = 1 L

Wt. of solutions =

V \times d e n s i t y = 1000 \times 1.253 = 1253 g

Wt. of solute =

1253 \times 22 % = 257.66

Moles. of solute =

\frac{275.66}{342} = 0.806

Wt. of solvent =

1253 - 257.66 = 977.34

Molarity =

\frac{m o l e s o f s o l u t e}{V o l u m e o f s o l u t i o n} = 0.806 M

Normality =

6 \times M o l a l i t y = 6 \times 0.806 = 4.836 N

Molalit =

\frac{M o l e s o f s o l u t e}{W t . o f s o l v e n t i n k . g} = \frac{0.806}{977.34 / 1000} = 0.825 m

Question 11. The molecular mass of benzoic acid in benzene, as determined by depression in freezing point method, corresponds to:

ionization of benzoic acid
dimerization of benzoic acid
trimerization of benzoic acid
solvation of benzoic acid

Answer: Option B
: B

Benzoic acid undergoes association in benzene i.e. it dimerizes.

Question 12. Boiling point of chloroform was raised by 0.323 K, when 0.5143 g of anthracene was dissolved in 35 g of chloroform. Molecular mass of anthracene is(

= 3.9 kg mol-1)

79.42 g/mol
132.32 g/mol
177.42 g/mol
242.32 g/mol

Answer: Option C
: C

Boiling Point Of Chloroform Was Raised By 0.323 K, When 0.51....

Question 13. Two isotonic solutions must have ----

Same solute and solvent
Same solute but different solvent
Same solvent but different solute
Both Solute and solvent may be different.

Answer: Option D
: D

For two solutions to be isotonic only requirement is that their osmotic pressures should be same. There are no conditions on solutes and solvents.

Question 14. If

α

is the degree of dissociation of

N a_{2} S O_{4}

, the vant Hoff's factor (i) used for calculating the molecular mass is

1+α
α
1+2α
1−2α

Answer: Option C
: C

N a_{2} S O_{4}      1 - α ⇌ 2 N a^{+}      2 α + S O_{4}^{2 -}      α

Totalno. ofionsafter dissociation =

1 + 2 α

vant Hoff's factor,

i = \frac{N o . o f p a r t i c l e s a f t e r d i s s o c i a t i o n}{N o . o f p a r t i c l e s b e f o r e d i s s o c i a t i o n} = 1 + 2 α

Question 15. Which of the followings is a colligative property

Osmotic pressure
Boiling point
Vapour pressure
Freezing point

Answer: Option A
: A

Only Osmotic pressure is a colligative property. ‘Relative lowering of vapour pressure of the solvent’ is a colligative property but not only vapour pressure. Similar argument for boiling point and freezing point

Question 16. Osmotic pressure of a solution containing 0.1 mole of solute per litre at 273K is (in atm)

0.11×0.08205×273
0.1×1×0.08205×273
10.1×0.08205×273
0.11× 2730.08205

Answer: Option A
: A

Osmoticpressure,

π = C R T = \frac{n}{V} R T = \frac{0.1}{1} \times 0.08205 \times 273 a t m

Question 17. The average osmotic pressure of human blood is 7.8 bar at 370C. What is the concentration of an aqueous NaCl solution that could be used in the blood stream

0.16 mol/L
0.32mol/L
0.60mol/L
0.45mol/L

Answer: Option B
: B

Question 18. A 0.001 molal solution of

[P t (N H_{3})_{4} c l_{4}]

in water had a freezing point depression of

{0.0054}^{\circ}

. If

K_{f}

for water is 1.80, the correct formulation for the above molecule is

[Pt(NH3)4Cl3]Cl
[Pt(NH3)4]Cl4
[Pt(NH3)4Cl2]Cl3
[Pt(NH3)4Cl2]Cl2

Answer: Option D
: D

△ T = i K_{f} m

\Rightarrow i = \frac{△ T_{f}}{K_{f} m} = \frac{0.0054}{1.80 \times 0.001} = 3

Thus complexproducesthreeionspermolecule.hence possiblecorrectformulais

[P t (N H_{3})_{4} C l_{2}] C l_{2}

Question 19. The relative lowering of vapour pressure produced by dissolving 71.5 g of a substance in 1000 g of water is 0.00713. The molecular weight of the substance will be

180
342
60
18.0

Answer: Option A
: A

\frac{△ P_{1}}{P_{1}^{0}} = \frac{n_{2}}{n_{1} + n_{2}} \approx \frac{n_{2}}{n_{1}} = \frac{W_{2} / M_{2}}{W_{1} / M_{1}}

M_{2} = \frac{W_{2} \times M_{1}}{W_{1} \times (\frac{△ P_{1}}{P_{1}^{0}})} = \frac{71.5 \times 18}{1000 \times 0.00713} = 180.5 g / m o l e

Question 20. A non-ideal solution was prepared by mixing 30 ml chloroform and 50 ml acetone. The volume of mixture will be

> 80 ml
= 80 ml
≥ 80 ml

Answer: Option B
: B

Chloroform and Acetone solution shows negative deviation from Rault’s law.

H e n c e △ V m i x < 0

What Are Hydrocarbons What Is The Difference Between Saturated And Unsaturated Hydrocarbons Give Examples?

(a) Compounds of carbon and hydrogen are called hydrocarbons. For example, methane, ethane, etc. <br> (b) Saturated hydrocarbons contain carbon-carbon single bonds. <br> Unsaturated hydrocarbons contain at least one carbon-carbon double or triple bond.

What Are Saturated And Unsaturated Hydrocarbons Give A Chemical Test To Distinguish Between Saturated And Unsaturated Hydrocarbons?

Chemical test:- Bromine water test, if unsaturated hydrocarbons are added to it then the solution turns colourless. The unsaturated hydrocarbon decolourise bromine water. Whereas no change takes place to the solution when saturated hydrocarbons are added to bromine water.

What Is The Difference Between The Unsaturated And Saturated?

If more solute is added and it does not dissolve, then the original solution was saturated. If the added solute dissolves, then the original solution was unsaturated.

Do Basic Solution Reduced In Redox Reaction Is Called?

The oxidation and reduction reactions always occur simultaneously in the redox reaction or Oxidation-Reduction reaction. The substance getting reduced in a chemical reaction is known as the oxidizing agent, while a substance that is getting oxidized is known as the reducing agent.

How Do You Calculate The Molarity Of A Liquid?

The equation for calculating Molarity from the moles and volume is very simple. Just divide moles of solute by volume of solution.

How Do You Find Moles Given Liters And Molarity?

Compute the volume of a solution in liters, given the number of moles and molarity, by dividing the number of moles by the molarity in units of moles per liter. For example, a solution containing 6.0 moles and a having a molarity of 3.0 moles per liter has a volume of 2.0 moles per liter.

How Do You Find The Molality Of Two Solutions?

Molality Calculations:

The concentration of a solution can be given in moles of solute dissolved per kilogram of solvent.
Molality is given the symbol m.
molality = moles of solute ÷ mass of solvent in kilograms m = n(solute) ÷ mass(solvent in kg)

What Does The Molarity Of A Solution Indicate?

Molarity (M) is the amount of a substance in a certain volume of solution. Molarity is defined as the moles of a solute per liters of a solution. Molarity is also known as the molar concentration of a solution.

How Can You Describe A Solution?

A solution is a homogeneous mixture of one or more solutes dissolved in a solvent. Note that the solvent is the substance that is present in the greatest amount. Many different kinds of solutions exist. For example, a solute can be a gas, a liquid or a solid.

How Can You Make A Solution More Concentrated?

To make a solution more concentrated one should add more solute in solvent.

What Are The 8 Different Types Of Solution?

➤ Types of solutions :

Solid in solid :
Liquid in solid :
Gas in solid :
Solid in liquid :
Liquid in liquid :
Gas in liquid :
Solid in gas :
Liquid in gas :

What Is A Solution What Are The Properties Of Solution Class 9?

Properties of a Solution:

A solution is a homogeneous mixture. The constituent particles of a solution are smaller than 10-9 meters in diameter. Constituent particles of a solution cannot be seen by naked eyes. Solutions do not scatter a beam of light passing through it.

What Are Homogeneous Solutions?

A homogeneous mixture of two or more substances. Example: water, sugar, flavor mixture (Coke). The substances are physically combined, not chemically combined or bonded to each other.

What Are The Uses Of The Solutions?

Uses of Solutions:

Household cleaners like bleach are solutions, they help us to make our houses clean. Beverages such as fizzy drinks, mineral water and tea are solutions. 3.. In hydroponics, the roots of plants are immersed in solutions containing dissolved mineral salts.

What Are Two Main Types Of Solutions?

The solutions are of two forms, depending on whether the solvent is water or not.

Aqueous solution – When a solute is dissolved in water the solution is called an aqueous solution.
Non-aqueous solution – When a solute is dissolved in a solvent other than water, it is called a non-aqueous solution.

What Do You Mean By Concentration Of Solution Mention Two Ways Of Expressing The Concentration Of A Solution?

The concentration of solution =Amount of solventAmount of solute. Mainly one expresses concentration in 2 ways: (a) Mass by mass percentage: Mass of solute Mass by mass percentage of a solution =Mass of solutionMass of solute×100.

What Is Meant By Concentration Of A Solution?

A solution is a homogenous (fine) mixture of a substance (called solute) dissolved in another substance (called solvent). The amount of solute dissolved in a particular amount of the solvent is a crucial parameter and is called the concentration of the solution.

What Is Solution Mention Types?

The amount of solute present, solutions are classified into three types: unsaturated solutions and saturated solutions. Unsaturated solution: A solution in which more quantity of solute can be dissolved without raising its temperature, is called an unsaturated solution.

What Is The Purpose Of The Different Concentrations Of Solutions?

Chemists primarily need the concentration of solutions to be expressed in a way that accounts for the number of particles present that could react according to a particular chemical equation. Since percentage measurements are based on either mass or volume, they are generally not useful for chemical reactions.

Topics

What Are Hydrocarbons What Is The Difference Between Saturated And Unsaturated Hydrocarbons Give Examples?

What Are Saturated And Unsaturated Hydrocarbons Give A Chemical Test To Distinguish Between Saturated And Unsaturated Hydrocarbons?

What Is The Difference Between The Unsaturated And Saturated?

Do Basic Solution Reduced In Redox Reaction Is Called?

How Do You Calculate The Molarity Of A Liquid?

How Do You Find Moles Given Liters And Molarity?

How Do You Find The Molality Of Two Solutions?

What Does The Molarity Of A Solution Indicate?

How Can You Describe A Solution?

How Can You Make A Solution More Concentrated?

What Are The 8 Different Types Of Solution?

What Is A Solution What Are The Properties Of Solution Class 9?

What Are Homogeneous Solutions?

What Are The Uses Of The Solutions?

What Are Two Main Types Of Solutions?

What Do You Mean By Concentration Of Solution Mention Two Ways Of Expressing The Concentration Of A Solution?

What Is Meant By Concentration Of A Solution?

What Is Solution Mention Types?

What Is The Purpose Of The Different Concentrations Of Solutions?

Sub Topics

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