Class 11 CHEMISTRY Suggestion  2023

 

Annual Examination-2022-23 Class XI

Chemistry

Time: 3 Hours Max. Marks: 70

SECTION-A

Directions (Q. Nos. 1-18) : The following questions are multiple-choice questions

with one correct answer. Each question carries 1 mark. There is no
internal choice in

this section.

Q.1 Which of the following units of concentration is temperature
dependent?

(a) Molality (b) Mole fraction (c) Molarity (d) Weight percentage

Q.2 The amount of 70% HNO3 required to prepare 250 ml of 2.0 M HNO3 is

(a) 54.0 g (b) 45.0 g
(c) 90.0 g (d) 70.0 g

Q.3 Find the molarity of 98% H2SO4 solution at 35℃ with
density equal to 1.84g/cc.

(a) 18.4 M (b) 18 M (c) 8.14 M (d) 4.18 M

Q.4 The radius of an atomic nucleus is of the order of————–

(a) 10-10 cm (b)
10-13 cm
(c)10-15 cm (d)
10-8 cm

Q.5 Which of the following pairs represents isobars?

(a) 3He2 and 4He2 (b) 24Mg12 and 25Mg12 (c) 40K19 and 40Ca20 (d) 40K19 and 39K19

Q.6 The atomic orbital is ————–

(a) The circular path of the electron (b) Elliptical shaped Orbit (c)
Threedimensional

field around nucleus (d) The region in which there is a maximum

probability of finding an electron.

Q.7 Which of the following is not permissible?

(a) n= 4, l = 3, m= 0 (b) n= 4, l = 2, m= 1 (c) n= 4, l = 4, m= 1 (d) n=
4, l = 0, m= 0

Q.8 According to Aufbau principle a new electron enters the orbitals when:

(a) (n + l) is minimum (b) (n + l) is maximum (c) (n + m) is minimum (d)
(n +

m) is maximum

Q.9 Which of the following statements is incorrect?

(a) I.E.1 of O
is lower than that of N but I.E.2 of O is higher than that of N (b) The

enthalpy of N to gain an electron is almost zero but of P is 74.3 kJ mol-1 (c)

Isoelectronic ions belong to the same period (d) The covalent radius of
iodine is

less than its Van der Waal’s
radius

Q.10 Which one has a pyramidal shape?

(a) SO3 (b)
PCl3 (c) CO3

2- (d) NO3

–

Q.11 Sp3d2 hybridization is present in [Co(NH3)6]3+, find
its geometry

(a) octahedral geometry (b) square planar geometry (c) tetragonal geometry
(d)

tetrahedral geometry

3

Q.12 The dihedral angle in the staggered conformation of C2H6 is

(a) 1200 (b) 600 (c) 00 (d) 900

Q.13 Bond length of (I) ethane, (II) ethene, (III) acetylene and (IV)
benzene

follows the order:

(a) I > II > III > IV (b) I > II > IV> III (c) I > IV
> II > III (d) III > IV > II > I

Q.14 Benzene reacts with CH3Cl in the presence of anhydrous AlCl3 to form

(a) Chlorobenzene (b) Benzyl chloride (c) xylene (d) toluene

Q.15 What happens when a mixture of acetylene and hydrogen is passed over

heated Lindlar’s catalyst?

(a) Ethylene and water are formed (b) Ethane and water are formed (c)
Ethylene

is formed (d) Acetylene and ethane are formed

Q.16 Assertion : BF3 molecule has zero dipole moment.

Reason : F is
electronegative and B–F
bonds are polar in nature.

(a) Both Assertion and Reason are correct and Reason is a correct
explanation of the Assertion.

(b) Both Assertion and Reason are correct but Reason is not the a correct

explanation of the Assertion.

(c) Assertion is correct but Reason is incorrect.

(d) Both the Assertion and Reason are incorrect.

Q.17 Assertion : Sulphur compounds like SF6 and H2SO4 have
12 valence

electrons around S atom.

Reason : All
sulphur compounds do not follow octet rule.

(a) Both Assertion and Reason are correct and Reason is a correct
explanation of the Assertion.

(b) Both Assertion and Reason are correct but Reason is not the a correct

explanation of the Assertion.

(c) Assertion is correct but Reason is incorrect.

(d) Both the Assertion and Reason are incorrect.

Q.18 Assertion : Second ionization enthalpy will be higher the
first ionization enthalpy.

Reason : Ionization
enthalpy is a quantitative measure of the tendency of an

element to lose electron.

(a) Both Assertion and Reason are correct and Reason is a correct
explanation of the Assertion.

(b) Both Assertion and Reason are correct but Reason is not the a correct

explanation of the Assertion.

(c) Assertion is correct but Reason is incorrect.

(d) Both the Assertion and Reason are incorrect.

SECTION-B

Directions (Q. No. 19-25) : This section contains 7 questions with internal choice in one question. The following questions are very short answer type and
carry 2 marks each.

Q.19 Explain Kharasch Effect with example.

Q.20 Based on Le-chatelier’s principle state three conditions by which the point of equillibrim in the following reaction can be shifted towards forward
direction.

Q.21 (i) Which among the following is anti-aromatic?

 

(ii) What happened when acetylene is passed through red hot tube at 873 K.

Q.22 All the C-O bonds in carbonate ion (CO3

2–) are
equal in length. Explain with

proper structures. What is the C-O bond order in carbonate ion (CO3

2–)?

Q.23 A medicine company make 500 mg tablet with 50% (w/w) paracetamol

content. Molar mass of paracetamol is150 g/mole approximately.

(i) How many paracetamol molecules are present in each table ?

(ii) What is the molar concentration if one tablet is dissolved in 250 ml
glass of

water ?

Q.24 Arrange the followings in increasing order of properties as indicated
against

it:

(i) Al+3, Na+, F–, Mg+2 (size)

(ii) C, N , B, O (ionization potential)

OR

Q.24 Arrange the followings in decreasing order of properties as indicated
against

it:

(i) I, Cl, F, Br (electron affinity)

(ii) Li, K, Na, Rb (basic property)

Q.25 Derrive the relation between Kp and Kc.

Section-C

6

Directions (Q. No. 26-30) : This section contains 5 questions. The following

questions are short answer type and carry 3 marks each.

Q.26 (i) Arrange the following according to their stability: KO2, Na2O2, H2.

(ii) Which one has more dipole moment and why: NH3 and NF3. (1+2)

Q.27 An alkyl halide C5H11Br (A) reacts with ethanolic KOH to give an alkene

‘B’, which reacts with
Br2 to give a compound ‘C’,
which on dehydrobromination

provides an alkyne with ‘D’.
On treatment with sodium metal in liquid ammonia, one mole of ‘D’ gives
one mole of the sodium salt of ‘D’ and half a mole of hydrogen gas. Complete
hydrogenation of ‘D’ yields a straight-chain
alkane.

Identify A, B, C and D. Give the reactions involved.

Q.28 (i) Which
of will have smallest de-Broglie wavelength : N2, O2,He+2,electron?

(ii) Match the quantum numbers with the
information provided by these. (1+2)

Quantum number Information provided

(i) Principal quantum number (a) orientation of the orbital

(ii) Azimuthal quantum number (b) energy and size of orbital

(iii) Magnetic quantum number (c) spin of electron

(iv) Spin quantum number (d) shape of the orbital

Q.29 Convert the following: (i) Phenol to benzene (ii) Chlorabenzene to
benzene

(iii) Phenyl magnesium bromide to benzene. (1+1+1)

Q.30 (i) What happen: Benzene is treated with hydrogen in presence of Ni

catalyst.

(ii) Convert: (a) Benzene to glyoxal (b) Benzene to Lindane. (1+2)

 

SECTION-D

Directions (Q. No. 31-32) : The following questions are case-based questions. Each

question carries 4 marks. Read the passage carefully and answer the
questions that

follow.

Q.31 We must bear in mind that when Mendeleev developed his Periodic
Table,

chemists knew nothing about the internal structure of atom. However, the
beginning of the 20th century witnessed profound developments in theories about
sub-atomic particles. In 1913, the English physicist, Henry Moseley observed
regularities in the characteristic X-ray spectra of the elements. A plot of ν (whereν
is frequency of Xrays emitted) against atomic
number (Z ) gave a straight line and not the plot of ν vs atomic mass. He thereby showed that the atomic number is a more
fundamental property of an element than its atomic mass. Mendeleev’s
Periodic Law was, therefore, accordingly modified. This is known as the Modern Periodic Law
and can

be stated as : The physical and chemical properties of the elements are
periodic

functions of their atomic numbers.Numerous forms of Periodic Table have
been devised from time to time. Some forms emphasise chemical reactions and
valence,whereas others stress the electronic configuration of elements. A modern
version, the

so-called “long form” of the Periodic Table of
the elements , is the most convenient and widely used. The horizontal rows (which Mendeleev called series) are
called periods and the vertical columns, groups. Elements having similar outer
electronic configurations in their atoms are arranged in vertical columns, referred
to as groups or families. According to the recommendation of International Union of Pure
and

Applied Chemistry (IUPAC), the groups are numbered from 1 to 18 replacing
the older notation of groups
IA … VIIA, VIII, IB … VIIB and 0. There are altogether seven periods. The period number corresponds to the highest principal
quantum number (n) of the elements in the period. The first period contains 2
elements. The subsequent periods consists of 8, 8, 18, 18 and 32 elements, respectively.
The seventh period is incomplete and like the sixth period would have a theoretical
maximum (on the basis of quantum numbers) of 32 elements. In this form of the Periodic
Table, 14 elements of both sixth and seventh periods (lanthanoids and actinoids,
respectively)

are placed in separate panels at the bottom. the IUPAC has made
recommendation that until a new element’s
discovery is proved, and its name is officially recognised, a systematic nomenclature be derived directly from the atomic number of the
element using the numerical roots for 0 and numbers 1-9. The roots are put
together in order of digits which make up the
atomic number and “ium” is added at the end. Groupwise

Electronic Configurations Elements in the same vertical column or group
have similar valence shell electronic configurations, the same number of electrons in
the outer orbitals, and similar properties. theoretical foundation for the periodic
classification.

The elements in a vertical column of the Periodic Table constitute a group
or family and exhibit similar chemical behaviour. This similarity arises because
these elements have the same number and same distribution of electrons in their outermost
orbitals.

We can classify the elements into four blocks viz., s-block, p-block,
d-block and fblock depending on the type of atomic orbitals that are being filled with
electrons.

Two exceptions to this categorisation. Strictly, helium belongs to the
s-block but its positioning in the p-block along with other group 18 elements is justified
because it has a completely filled valence shell (1s) and as a result, exhibits
properties characteristic of other noble gases. The other exception is hydrogen. It
has only one selectron

and hence can be placed in group 1 (alkali metals). It can also gain an

electron to achieve a noble gas arrangement and hence it can behave
similar to a group

17 (halogen family) elements. Because it is a special case, we shall place
hydrogen

separately at the top of the Periodic Table.

(i) How did Moseley interpret the result of X-ray spectra experiment?

(ii) Modern periodic table is classified in how many blocks? What are the
exception ?

(iii) What are d-block elements ? Give Characteristics of d-block elements
.

(iv) Give characteristics of nobel gas elements .

Q.32 When a liquid evaporates in a closed
container, molecules with relatively

higher kinetic energy escape the liquid surface into the vapour phase and
number

of liquid molecules from the vapour phase strike the liquid surface and
are retained

in the liquid phase. It gives rise to a constant vapour pressure because
of an

equilibrium in which the number of molecules leaving the liquid equals the

number returning to liquid from the vapour. We say that the system has
reached

equilibrium state at this stage. However, this is not static equilibrium
and there is a

lot of activity at the boundary between the liquid and the vapour. Thus,
at

equilibrium, the rate of evaporation is equal to the rate of condensation.
It may be

9

represented by

H2O(l) ⇌ H2O(vap)

The double half arrows indicate that the processes in both the directions
are going

on simultaneously. The mixture of reactants and products in the
equilibrium state

is called an equilibrium mixture.

Equilibrium can be established for both physical processes and chemical
reactions.

The reaction may be fast or slow depending on the experimental conditions
and the

nature of the reactants. When the reactants in a closed vessel at a
particular

temperature react to give products, the concentrations of the reactants
keep on

decreasing, while those of products keep on increasing for some time after
which

there is no change in the concentrations of either of the reactants or
products. This

stage of the system is the dynamic equilibrium

The chemical equilibrium may be classified in three groups.

i) The reactions that proceed nearly to completion and only negligible

concentrations of the reactants are left. In some cases, it may not be
even possible

to detect these experimentally.

ii) The reactions in which only small amounts of products are formed and
most of

the reactants remain unchanged at equilibrium stage.

(iii) The reactions in which the concentrations of the reactants and
products are

comparable, when the system is in equilibrium.

Solid-Liquid Equilibrium Ice and water kept in a perfectly insulated thermos
flask

(no exchange of heat between its contents and the surroundings) at 273K
and the

atmospheric pressure are in equilibrium state and the system shows
interesting

characteristic features. We observe that the mass of ice and water do not
change

with time and the temperature remains constant. However, the equilibrium
is not

static. The intense activity can be noticed at the boundary between ice
and water.

Molecules from the liquid water collide against ice and adhere to it and
some

molecules of ice escape into liquid phase. There is no change of mass of
ice and

water, as the rates of transfer of molecules from ice into water and of
reverse

transfer from water into ice are equal at atmospheric pressure and 273 K.
It is

obvious that ice and water are in equilibrium only at particular
temperature and

pressure. For any pure substance at atmospheric pressure, the temperature
at which

the solid and liquid phases are at equilibrium is called the normal melting
point or

normal freezing point of the substance. The system here is in dynamic
equilibrium

10

and we can infer the following: (i) Both the opposing processes occur

simultaneously.

(ii) Both the processes occur at the same rate so that the amount of ice
and water

remains constant.

Solid – Vapour Equilibrium Let us now
consider the systems where solids sublime

to vapour phase. If we place solid iodine in a closed vessel, after
sometime the

vessel gets filled up with violet vapour and the intensity of colour
increases with

time. After certain time the intensity of colour becomes constant and at
this stage

equilibrium is attained. Hence solid iodine sublimes to give iodine vapour
and the

iodine vapour condenses to give solid iodine. The equilibrium can be
represented

as,

I2(solid) ⇌ I2(vapour)

Other examples showing this kind of equilibrium are,

Camphor(solid)
⇌
Camphor(vapour)

NH4Cl(solid)
⇌
NH4Cl(vapour)

The equilibrium Involving Dissolution of Solid in
Liquids Only a limited amount of

salt or sugar can dissolves in a given amount of water at room
temperature. If we

make a thick sugar syrup solution by dissolving sugar at a higher
temperature,

sugar crystals separate out if we cool the syrup to the room temperature.
We call it

a saturated solution when no more of solute can be dissolved in it at a
given

temperature. The concentration of the solute in a saturated solution
depends upon

the temperature. In a saturated solution, a dynamic equilibrium exits
between the

solute molecules in the solid state and in the solution: Sugar (solution)
Sugar

(solid), and the rate of dissolution of sugar = rate of crystallisation of
sugar.

Equality of the two rates and dynamic nature of equilibrium has been
confirmed

with the help of radioactive sugar. If we drop some radioactive sugar into
saturated

solution of non-radioactive sugar, then after some time radioactivity is
observed

both in the solution and in the solid sugar. Initially there were no
radioactive sugar

molecules in the solution but due to dynamic nature of equilibrium, there
is

exchange between the radioactive and non-radioactive sugar molecules
between

the two phases. The ratio of the radioactive to non- radioactive molecules
in the

solution increases till it attains a constant value.

(i) Explain Solid- Vapour equilibrium with help of suitable example.

11

(ii) What is dynamic equilibrium?

(iii) Explain the equilibrium Involving Dissolution of Solid in Liquids
with

suitable example.

(iv) The concentration of the solute in a saturated solution depends upon
the

…….. Fill the blank.

SECTION-E

Directions (Q. No. 33-35) : The following questions are long answer type and carry 5
marks each.

Q.33 (i) Identify X, Y and Z in the following reaction:

(ii) Convert: (a) Benzene to benzoic acid (b) O-xylene to Pthalic acid.

Q.34 (i) Explain: Grignard reagent should be prepared in anhydrous
condition.

(ii) Write the limitation of Wurtz reaction.

(iii) Write short notes with example: Corey-House Reaction.

(iv) Convert: Methane to Acetic Acid.

Q.35 (i) What are the pyrolysis products of hexane. Write IUPAC name of
all the products.

(ii) Complete the following reaction:

 

 

OR

Q.35 (i) Complete the following:

(ii) Write the major product in the following reaction: