Question Set C

CBSE 11th Chemistry Organic Chemistry - Some Basic Principles and Techniques Model Questions Papers Study Material - QB365

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Questions:

Generic 3

7 x 3 = 21

Arrange the following in order of increasing O.N of iodine: I₂, HI, HIO₂, KIO₃, ICI

Calculate the de Broglie wavelength of an electron moving with 1% of the speed of light?

Give condensed and bond line structural formulas and identify the functional group(s) present, if any, for :
(a) 2,2,4-Trimethylpentane
(b) 2-Hydroxy-1,2,3-propanetricarboxylic acid
(c) Hexanedial

At 1127 K and 1 atm pressure, a gaseous mixture of CO and CO_2,in carbon has 90.55% CO by mass \(C(S)+C{ O }_{ 2 }(g)\rightleftharpoons 2CO(g)\)
Calculate K_c for this reaction at the above temperature.

The molar heat of formation of NH₄NO₃ (s) is -367.54 kJ and those of N₂ O(g) and H₂O(i) are + 81.46 kJ and -258.78 kJ respectively at 25^oC and 1.0 atmospheric pressure. Calculate \(\Delta \)H and \(\Delta \)U for the reaction.

Consider the following species : N^3–, O^2–, F^– , Na⁺, Mg²⁺ and Al³⁺
(a) What is common in them?
(b) Arrange them in the order of increasing ionic radii.

A Welding fuel gas contains carbon and hydrogen only. Buring a small sample of it in oxygen gives 3.38g carbon dioxide, 0.690 g of water and no other products. A volume 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g.
(a) Calculate. Molar mass of the gas.
(b) Calculate. molecular formula.

Generic 2

8 x 2 = 16

What do you understand by catenation.

What is PAN stands for?

10.

Explain the principle of paper chromatography.

11.

What are degenerate orbitals?

12.

Does the oxidation number of an element in any molecule or any polyatomic ion represent the actual charge on it?

13.

What do you understand by bond pairs and lone pairs of electrons? Illustrate by giving one exmaple of each type.

14.

Why is the energy of \({ \pi 2p }_{ x }\) and \({ { \pi 2p } }_{ y }\) molecular orbital lower than \({ \sigma 2p }_{ z }\) molecular orbital in \({ N }_{ 2 }\) molecule?

15.

Neutrons can be found in all atomic nuclei except in one case. Which is this atomic nucleus and what does it consist of ?

1 Marks

3 x 1 = 3

16.

Why do hydrides and halides of Be polymerise?

17.

Why are potassium and caesium,rather than lithium used in photioelectric cells?

18.

Why are the gases helium and hydrogen not liquefied at room temperature by applying very high pressure?

Generic 5

1 x 5 = 5

19.

Pressure versus volume graph for a real gas and an ideal gas are shown in figure. Answer the following questions on the basis of the graph.

Interpret the behaviour of real gas with respect to ideal gas at high pressure.

Multiple Choice Question

10 x 1 = 10

20.

A catalyst will increase the rate of a chemical reaction by ______.

(a)

shifting the equilibrium to the right

(b)

shifting the equilibrium to the left

(c)

lowering the activation energy

(d)

increasing the activation energy

21.

The average kinetic energy of the gas molecule is

(a)

inversely proportional to its absolute temperature

(b)

directly proportional to its absolute temperature

(c)

equal to the square of its absolute temperature

(d)

All of the above

22.

Which of the following is a purely acidic oxide?

(a)

Si0₂

(b)

Sn0₂

(c)

PbO

(d)

Mn0₂

23.

The pollutant released in Bhopal gas tragedy was

(a)

Ammonia

(b)

Mustard gas

(c)

Nitrous oxide

(d)

Methyl isocyanate

24.

sp³, sp² and sp hybridized carbon atom, the p character is maximum in:______.

(a)

sp³

(b)

sp²

(c)

(d)

all of the above have same p-character

25.

A co-ordinate bond is formed by ______.

(a)

sharing of electrons contributed by both the atoms

(b)

complete transfer of electrons

(c)

sharing of electrons contributed by one atom only

(d)

none of these

26.

Hydrogen is obtained as a by-product in the

(a)

electrolysis of water

(b)

manufacture of caustic soda

(c)

Bosch process

(d)

Lane process

27.

Water may be softened using

(a)

sodium aluminium silicate

(b)

Graham's salt

(c)

an ion exchange resin

(d)

trisodium phosphate

28.

The highest ionization energy is exhibited by _____.

(a)

halogens

(b)

alkaline earth metals

(c)

transition metals

(d)

noble gases

29.

The enthalpies of all elements in their standard states are: _______.

(a)

unity

(b)

zero

(c)

(d)

different for each element

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Answers Key:

Generic 3

7 x 3 = 21

The increasing order is
HI < I₂ < ICI < HIO₂ < KIO₃

According to de Broglie equation,\(\lambda =\frac { h }{ mv } \)
Mass of electron = 9.1 x 10^-31 kg; Planck's constant = 6.626 x 10^-34 kgm²s^-1
Velocity of electron = 1% of speed of light = 3.0 x 10⁸x 0.01 = 3 x 10⁶ me-1
Wavelength of electron (\(\lambda \)) =\(\frac { h }{ mv } =\frac { (6.626x10^{ -34 }kgm^{ 2 }s^{ -1 }) }{ (9.1x10^{ -31 }kg)x(3x10^{ 6 }ms^{ -1 }) } \)
= 2.43 x 10^-10 m.

(a) 2, 2, 4-trimethylpentane
Condensed formula: (CH₃)₂CHCH₂C (CH₃)₃
Bond line formula:

(b) 2-hydroxy-1, 2, 3-propanetricarboxylic acid
Condensed Formula: (COOH)CH₂C(OH) (COOH)CH₂(COOH)
Bond line formula:

The functional groups present in the given compound are carboxylic acid (-COOH) and alcoholic (-OH) groups.
(c) Hexanedial Condensed Formula: (CHO) (CH₂)₄ (CHO)
Bond line Formula:

The functional group present in the given compound is aldehyde (-CHO).

Let the total mass of the gaseous mixture = 100 g.
Mass of CO = 90.55 g
And, mass of CO₂= (100 – 90.55) = 9.45 g
Now, the number of moles of CO, nCO\(=\frac{90.55}{28}\)=3.234mol
Number of moles of CO₂,nCO₂\(=\frac{9.45}{44}\)=0.215mol
The partial pressure of CO,
pCO=nCOnCO+nCO2×ptotal
\(= \frac{3.234}{3.234+0.215}×1 \)= 0.938 atm
Partial pressure of CO₂,
pCO₂ = nCO₂nCO+nCO₂×ptotal
\(=\frac{ 0.215}{3.234+0.215}×1\)=0.062atm
Kp=P2COPCO2 = (0.938)20.062=14.19
For the given reaction,
Δng= 2 –1 = 1
We know that,
KP=KC(RT)Δn
14.19= KC(0.082×1127)1
\(KC=\frac{14.19}{0.082×1127}\)
= 0.153

\(\mathrm{NH}_4 \mathrm{NO}_3(s) \longrightarrow \mathrm{N}_2 \mathrm{O}(g)+2 \mathrm{H}_2 \mathrm{O}(l) \)
\( \Delta H_{\text {Reaction }}=\Delta H_{\text {Products }}-\Delta H_{\text {Reactants }} \)
\( =\Delta H_{\mathrm{N}_2 \mathrm{O}}+2 \times \Delta H_{\mathrm{H}_2 \mathrm{O}}-\Delta \mathrm{H}_{\mathrm{NH}_4 \mathrm{NO}_3} \)
\( =81.46+2(-285.8)-(-367.57) \)
\( \Delta H=-122.560 \mathrm{~kJ} \)
\( \Delta H=\Delta E+\Delta n R T \)
\( -122560=\Delta E+1 \times 8.314 \times 298 \)
\( \Delta E=-125037 \mathrm{~J} \)
\(=-125.037 \mathrm{~kJ}\)

(a) All the given species have a same number of electrons \(({ 10e }^{ 1 })\)Therefore, all are isoelectronic species.
(b) The ionic radii of isoelectronic species decreases with increase in atomic number (as magnitude of the nuclear charge increase with increase in atomic number)
Therefore, their ionic radii increase in the order.\(\underset { z=13 }{ { Al }^{ 3+ } } <\underset { 12 }{ { Mg }^{ 2+ } } <\underset { 11 }{ { Na }^{ + } } <\underset { 9 }{ { F }^{ - } } <\underset { 8 }{ { O }^{ 2 } } <\underset { 7 }{ { N }^{ 3- } } \)

(a) Calculation for molar of the gas
10.0 L of the given gas at STP weigh = 11.6 g
\(\therefore \) 22.4 L of the given gas at STP will weigh
\(\frac { 11.6\times 22.4 }{ 10 } =25.984\quad g\)
Molar mass = 25.984 = 26 \({ mol }^{ -1 }\)
(b) Empirical formula mass (CH) = 12 + 1 = 13
\(\therefore \) \(n=\frac { molecular \ mass }{ empirical \ formula \ mass } =\frac { 26 }{ 13 } =2\)
Hence, molecular formula
\(=n\times CH=2\times CH={ C }_{ 2 }{ H }_{ 2 }\)

Generic 2

8 x 2 = 16

Catenation: The property to form chains or rings not only with single bonds but also with multiple bonds with itself is called catenation.
For example, carbon forms chains with (C - C) single bonds and also with multiple bonds (C = C or C \(\equiv \) C).

It is peroxyacetyl nitrate.

10.

This is the simplest form of chromatography. Here a strip of paper acts as an adsorbent. It is based on the principle which is partly adsorption. The paper is made of cellulose fibres with molecules of water adsorbed on them. This acts as stationary phase. The mobile phase is the mixture of the components to be identified prepared in a suitable solvent.

11.

Orbitals having same energy belonging to the same subshell.

12.

No, the oxidation number of an element in any species is an apparent charge on the atom which it appears to have acquired when all other atoms in the species are removed as ions.

13.

Covalent bond is formed by mutual sharing of electrons. The shared pair of electrons present between the bonded atoms are called bond pairs of electrons and unshared pair (non-bonding) electrons are called the lone pairs of electrons. e.g., ammonia, NH₃ contains 3 bond pairs and 1 lone pair of electrons, whereas CH₄ contains only 4 bond pairs.

14.

This is because of intermixing of 2s and 2p_z orbitals because of their close proximity. Due to intermixing, \({ \sigma 2p }_{ z }\) molecular orbital becomes higher in energy than \({ \pi 2p }_{ x }\) and \({ { \pi 2p } }_{ y }\) molecular orbitals.

15.

In case of hydrogen atom, there is no neutron. It consists of only one proton