Question Set D

CBSE 12th Standard Chemistry Amines HOT Questions Study Material - QB365

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Questions:

Which type of ionic substances shown Schottky defect in solids?

Name two physical quantites that remain unaffected when a reversible reaction is carried out in the presence of a catalyst.

Name the electrophile produced in the reaction of benzene with benzoyl chloride in the presence of anhydrous AlCl₃. Name the reaction also.

In a compoubd, nitrogen atoms (N) make cubic close packed lattice and metal atoms (M)occupy one-third of the tetrahedral voids present. Determine the formula of the compound formed by M and N?

The rate law for the decomposition of N₂O₅ is : rate = k[N₂O₅]. What is the significance of k in this equation ?

Give reasons for the following : Variations in the radii of transition elements are not as pronounced as those of representative elements.

Define azeotropic mixture.

(a) Calculate \(\Delta G°\)for the reaction Mg_(s)+Cu²⁺\(\rightarrow\)Mg²⁺_(aq)+Cu_(s)
Given: \({ E }_{ cell }^{ ° }\)= +2.7V, 1F = 96500 C mol^-1
(b) Name the type of cell which was used in Apollo space programme for providing electrical power.

Identify the four groups into which the polymers are classified on the basis of the magnitude of intermolecular forces present in them. To which group or groups do polythene and bakelite belong ?

10.

Calculate the Avogadro's number from the following data of AB when has NaCl type structure :
Density of AB = 2.48 g cm^-3, M = 58
Distance between A⁺ and B^- in AB = 269 pm.

11.

45 g of ethylene glycol (C₂H₄O₂) is mixed with 600 g of water. Calculate
(i) the freezing point depression and
(ii) the freezing point of the solution.

12.

At 10\(°\) C, the average osmotic pressure of blood is 8.8 atm. Find the total concentration of the various constituents in the blood. Assuming that the concentration is the same as the molarity, find the freezing point of the solution (K_f for water = 1.86 K kg mol^-1)

13.

A 100W and 110 V incandescent lamp is connected in series with an electrolytic cell containing CdSO₄ solution. What mass of cadmium will be deposited at the cathode after 4 hrs of electricity?

14.

If the position of Na⁺ and Cl^- are interchanged in NaCl having fcc arrangement of Cl ions then in the unit cell of Nacl^- ions then in the unit cell of Nacl

(a)

Na⁺ ions will decrease by 1 while Cl^- ions will increase by 1

(b)

Na⁺ ions will increase by 1 while Cl^- ions will decrease by 1

(c)

Number of Na⁺ and Cl^- ions will remain the same

(d)

The crtystal structure of NaCl will change

15.

A chemical reaction was carried out at 300 K and 280 K the rate constants were found to be K₁ and K₂ respectively. Then

(a)

K₂ = 4K₁

(b)

K₂ = 2K₁

(c)

K₂ = 0.25 K

(d)

K₂ = 0.5 K₁

16.

Two liquids X and Y form an ideal solution. The mixture has a vapour pressure of 400 mm at 300 K when mixed in the molar ratio of 1:1 and a vapour pressure of 350 mm when mixed in the molar ratio of 1:2 at the same temperature. The vapour pressures of the pure liquids X and Y respectively are

(a)

250 mm, 550 mm

(b)

350 mm, 450 mm

(c)

350 mm, 700 mm

(d)

500 mm, 500 mm

(e)

550 mm, 250 mm

17.

The equivalent conductance of NaCl at concentration C and at infinite dilution are \({ \lambda }_{ c }\) and \({ \lambda }_{ \infty }\) respectively. The correct relationship between \({ \lambda }_{ c }\) and \({ \lambda }_{ \infty }\) is given by (where the constant B is positive)

(a)

\({ \lambda }_{ c }={ \lambda }_{ \infty }+(B)\sqrt { C } \)

(b)

\({ \lambda }_{ c }={ \lambda }_{ \infty }+(B) { C } \)

(c)

\({ \lambda }_{ c }={ \lambda }_{ \infty }-(B) { C } \)

(d)

\({ \lambda }_{ c }={ \lambda }_{ \infty }-(B)\sqrt { C } \)

18.

Bauxite ore is made up Al₂O₃ +SiO₂+TiO₂+Fe₂O₃.This ore treated with conc.NaOH solution at 500K and 35 bar pressure for few hours and filtered hot.In the filtrate ,the species present are:

(a)

NaAl(OH)₄only

(b)

NaTi(OH)₆only

(c)

NaAl(OH)₄and Na₂SiO₃ both

(d)

Na₂SiO₃ only

19.

General electronic configuration of actinoids is (n - 2) f^1-14 (n - 1) d^0-2 ns². Which of the following actinoids have one electron in 6d orbital?

(a)

U (Atomic no. 92)

(b)

Np (Atomic no. 93

(c)

Pu (Atomic no. 94)

(d)

Am (Atomic no. 95)

20.

Lead storage battery

21.

\([Co(NH_3)_6][Cr(CN)_6]\)

22.

RNA

23.

Antidepressant drug

24.

At constant temperature and volume, X decomposes as 2 X (g) \(\longrightarrow\) 3 Y (g) + 2 Z (g). P_x is the partial pressure of X.

Observation No.	Time (in minutes)	P_x (in mm of Hg)
1	0	800
2	100	400
3	200	200

(i) What is the order of reaction with respect to X?
(ii) Find the time for 75% completion of the reaction.
(iii) Find the total pressure when pressure of X is 700 mm of Hg.

25.

Benzene on reaction with HOCI in presence of an acid produces organic compound (A), (A) on treatment with NaNH₂/liq. NH₃ furnishes another organic compound (B). (B) on treatment with HBF₄ affords an organic compound (C) wich on heating with NaNO₂ gives organic compound (D). Identify (A), (B), (C) and (D).

26.

A house wife while working in the kitchen gots a cut on the finger. It started bleeding and become panicked. She immediately called her neighbour.She had kept ferric chloride in her house. She immediately applied it on the affected area and the bleeding stopped.
(i) What is the chemical formula of ferric chloride?
(ii) Why did bleeding stop on applying it on the affected finger?
(iii) What is the name of the phenomenon involved?
(iv) What do we learn from it? What is the value associated with this from the point of view of chemist?

27.

(a) Calculate the freezing point of solution when 1.9 g of MgCI₂ (M = 95 g mol^-1) was dissolved in 50 g of water, assuming MgCI₂ undergoes complete ionization. (K_f for water = 1.86 K kg mol^-1)
(b) (i) Out of 1 M glucose and 2 M glucose, which one has a higher boiling point and why?
(ii) What happens when the external pressure applied becames more than the osmotic pressure of solution?

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Answers Key:

()
Those ionic solids in which cation and anion are of almost similar size.

()
Equilibrium constant and enthalpy change.

Benzene, on reaction with benzoyl chloride gives benzophenone through an intermediate benzoylinium cation.

This is an example of Friedel-Crafts acylation reaction.

Suppose the atoms N in the ccp = n
\(\therefore \) No.of tetrahedral voids = 2n.
As rd of the tetrahedral voids are occupied by atoms M, therefore, no.of atoms M =\(\frac { 2n }{ 3 } \)
\(\therefore \) Ratio of M:N =\(\frac { 2n }{ 3 } \) :n = 2:3. Hence, the formula is M₂N₃.

k represents the rate constant or specific reaction for the reaction and is equal to the rate of reaction when concentration of N₂O₅ is 1 mol L^-1.

As we proceed along a transition series, the nuclear charge increases which tends to decrease the size but the addition of electrons in the d-subshell increases the screening effect which tends to counterbalance the effect of the increased nuclear charge

A mixture of liquids which has a definite composition and boils like a pure liquid is called azeotropic mixture.

(a) \(\Delta_{r} G^{\circ}=-n \mathrm{E}^{\circ} \mathrm{F}\)
= -2 x 2.71 V x 96500 C
= - 523030 J
= - 523.030 kJ mol^-1

Mg(s) \(\longrightarrow\) Mg²⁺+(aq) + 2e^-
Cu²⁺(aq) + 2e^- \(\longrightarrow\) Cu(s)
___________________________________
Mg(s) + Cu²⁺(aq) \(\longrightarrow\) Mg²⁺(aq) + Cu(s)
___________________________________

(b) H₂ -O₂ Fuel Cell was used in Apollo space programme for providing electrical power.

Elastomers: The polymers in which polymer chains are held together by weakest intermolecular forces.
Fibres: The polymers which are used for making fibres possess high tensile strength and high modulus.There are strong intermolecular forces of attraction like hydrogen bonding e.g. in nylon-66
Thermoplastics: The intermolecular forces of attraction in thermoplastic polymers are moderate.
Thermosetting polymers: These polymers are made from low molecular mass semi-liquid.These have stronger force of attraction due to cross linkage.
Bakelite is thermostting polymer.Polythene belongs to thermoplastics.

10.

6.0\(\times\) 10²³

11.

Depression in freezing point is related to the molality, therefore, the molality of the solution with respect to ethylene glycol \(=\frac{\text { moles of ethylene glycol }}{\text { mass of water in kilogram }}\)
\(\text {Moles of ethylene glycol }=\frac{45 \mathrm{~g}}{62 \mathrm{~g} \mathrm{~mol}^{-1}}=0.73 \mathrm{~mol}\)
\(\text {Mass of water in } \mathrm{kg}=\frac{600 \mathrm{~g}}{1000 \mathrm{~g} \mathrm{~kg}^{-1}}=0.6 \mathrm{~kg}\)
\(\text {Hence molality of ethylene glycol }=\frac{0.73 \mathrm{~mol}}{0.60 \mathrm{~kg}}=1.2 \mathrm{~mol} \mathrm{~kg}^{-1}\)
Therefore freezing point depression,
ÄT_f = 1.86 K kg mol^–1 x 1.2 mol kg^–1 = 2.2 K
Freezing point of the aqueous solution = 273.15 K – 2.2 K = 270.95 K

12.

Step-I : Calculation for concentration of the solution.
According to Van't Hoff's equation
p = CRT or C = \(\frac { \pi }{ RT } \)
p = 8.8 atm, T = 40\(°\)C = 313 K
R = 0.0821 L atm K^-1 mol^-1
\(C=\frac { 8.8 }{ 0.0821\times 313 } \)=0.34 molL^-1(M)
Step-II: Calculation of freezing point of the solution depression in freezing point of solution
\(\Delta\)T_f = K_f \(\times\) m
m = 0.34 mol kg^-1
(same as molarity as given)
K_f = 1.86 K kg mol^-1
\(\Delta\)T_f = 1.86 \(\times\) 0.84 (\(\because\) \(\Delta\) T_f = K_f m)
= 0.63 K = 0.63\(°\)C
Freezing point of the solution = 0 - 0.63 \(°\)C
= - 0.63\(°\) C

13.

Step I
Calculation of the quantity of charge passed:
We know that,
Watt = Ampere x Volt
Ampere =\(\frac { Watt }{ Volt } =\frac { 100 }{ 110 } \)
Now charge = Current x Time
=\(\left( \frac { 100 }{ 110 } amp \right) \times 4\times 60\times 60\)
= 13091 C
Step II
Calculation of mass of Cadmium deposited:
The cathodic reaction is
Cd²⁺_(aq)+2e^-\(\rightarrow\)Cd_(s)
112.2g 2 x 96500C
2 x 96500 C of charge deposited Cd = 112.2 g
13091 C charge will deposite Cd
\(\frac { 112.2g }{ 2\times 96500C } \times 13091C\)
= 7.61g

14.

In NaCl with fcc arrangement of Cl^- ions number of Cl^- ion=14,Na⁺ ions=13.On interchanging their positions,Cl^- ions will be 13 and Na⁺ ions will be 14

15.

(c) : For every 10^oC rise in temperature, rate constant is doubled, Hence, for 20^oC rise in temperature, rate constant will become 4 times, i.e., K₁= 4 K₂ or K₂ = 0.25 K₁

16.

(e)
550 mm, 250 mm

17.

(d)
\({ \lambda }_{ c }={ \lambda }_{ \infty }-(B)\sqrt { C } \)

18.

19.

(a)
U (Atomic no. 92)

20.

()
Pb is anode, PbSO₄ is cathode

21.

()
coordination

22.

()
Phosphodiester linkage

23.

()
Iproniazid

24.

(i) As pressure of X is changing with time, it cannot be a zero order reaction. Let us now check it for 1st order.
At t = 100 min, \(k={2.303\over 100}log{P_0\over P_t}={2.303\over 100}log {800\over 400}=6.932\times 10^{-3}min^{-1}\)
At t = 200 min, \(k={2.303\over 200}log{800\over 200}={2.303\over 800}log4=6.932\times10^{-3}min^{-1}\)
As k comes out to be constant, hence it is a reaction of 1st order
(ii)\(t_{75./.}={2.303\over k}log{100\over 100-75}={2.303\over 6.932\times10-3min}log4=200min\)
(iii) 2x (g)⟶ 3 y (g) + 2z (g)
Initial Pressure 800mm 0 0
Pressure after time t 800 - 2p 3 p 2 p
When pressure of X is 700 mm, 800 - 2 p = 700 or p = 50 mm
Total pressure = (800 - 2 p) + 3 p + 2 p = 800 + 3 p = 800 + 3 x 50 = 950 mm.

25.

(i) HOCI in presence of an acid generates the reactive electrophile, chloronium ion «r, which attacks benzene to give chlorobenzene (A).
(ii) Chlorobenzene (A) on treatment with NaNH2/liq. NH₃ undergaes-dehydrohalogenation via benzyne to afford aniline (B).
(iii) Aniline (B) on treatment with HBF4 forms the corresponding salt anilinium tetrafluoroborate (C) which on heating with NaNO₂ undergoes Balz-Schiemann reaction through the intermedium formation of benzenediazonium tetrafluoroborate to afford fluorobenzene (D).

26.

(i) Chemical formula of ferric chloride is FeCI₃.
(ii) Fe³⁺ ions of FeCl₃ neutralize the charge on the colloidal particles of blood. This leads to coagulation of blood. Bleeding therefore, stopped.
(iii) This phenomenon is known as coagulation or flocculation.
(iv) All house wives must keep small bag or kit in their kitchen. It must have ferric chloride kept in small bottle or potash alum, burnol and bandages etc. Minor accidents are very common in kitchen. The kit can be very helpful to deal with emergency skill of applying knowledge, helping others, kindness, etc are the values associated with it.

27.

(a) \(\Delta { T }_{ f }=i\frac { { K }_{ f }{ W }_{ b }\times 1000 }{ { M }_{ b }\times { W }_{ a } } \)
\(\Delta { T }_{ f }=3\times \left( \frac { 1.86\times 1.9 }{ 95\times 50 } \right) \times 1000\)
= 2.23 K
\(\Delta { T }_{ f }-{ \Delta T }_{ f }^{ ' }=\frac { 273.15-2.23 }{ 273-2.23 } \)
\({ T }_{ f }^{ ' }\) = 270.92 K or 270.77 K
(b) (i) 2 M glucose has a higher boiling point because higher the number of particles lesser is the vapour pressure.
(ii) Reverse osmosis.