MANAV RACHNA INTERNATIONAL SCHOOL
PT- 4 (2022-23) SET–B
Grade - XI
Subject – CHEMISTRY
Date: 21.2.2023
Time Allowed: 03 Hrs. Maximum Marks: 70
General Instructions:
Read the following instructions carefully.
There are 35 questions in this question paper with internal choice.
SECTION A consists of 18 multiple-choice questions carrying 1 mark each.
SECTION B consists of 7 very short answer questions carrying 2 marks each.
SECTION C consists of 5 short answer questions carrying 3 marks each.
SECTION D consists of 2 case- based questions carrying 4 marks each.
SECTION E consists of 3 long answer questions carrying 5 marks each.
All questions are compulsory.
Use of log tables and calculators is not allowed.
SECTION A
Q. No Questions Marks
1. What will be the molarity of a solution, which contains 5.85g of NaCl per 1
250mL?
(i) 4 mol L-1
(ii) 0.2 mol L-1
(iii) 2 mol L-1
(iv) 0.4 mol L-1
2. Which of the following contains the same number of carbon atoms as are in 6 g 1
of carbon (C-12) ?
(i) 6 g of ethane
(ii) 8 g of methane
(iii) 21 g of propane
(iv) 28 g of carbon monoxide
3 Which of the following spectral series for hydrogen atom lies in the visible 1
region of electromagnetic radiation?
(i) Lyman
(ii) Balmer
(iii) Paschan
(iv) Brackett
4 The elements in which 5f orbitals are progressively filled are called 1
(i) Actinides
Page 1 of 7 | Pre-board | Grade - XI | Set - B
(ii) Transition elements
(iii) Lanthanides
(iv) Halogens
5 The hybrid state of sulphur in SO2 molecule is : 1
(i) sp²
(ii) sp³
(iii) sp
(iv) sp³d
6 Which of the following oxides is amphoteric in character? 1
(i) SnO2
(ii) CO2
(iii) SiO2
(iv) CaO
7 Which of the following species, do not show disproportionation reaction? 1
(i) ClO–
(ii)ClO2–
(iii) ClO3–
(iv) ClO4–
8 ∆fUο of formation of CH4 (g) at certain temperature is –393 kJ mol–1. The value 1
of ∆fHο is
(i) zero
(ii) < ∆f Uο
(iii) > ∆fUο
(iv) equal to ∆fUο
9 Oxidation number of N in HNO3 is 1
(i) -3.5
(ii) +3.5
(iii) -5
(iv) +5
10 For any reversible reaction, if we increase concentration of the reactants, then 1
effect on equilibrium constant
(i) depends on amount of concentration
(ii) unchanged
(iii) decrease
(iv) increase
11 A base according to Bronsted concept is a substance which can 1
(i) lose a pair of electrons
(ii) donate protons
(iii) gain a pair of electrons
(iv) accept protons
12 The IUPAC name for 1
Page 2 of 7 | Pre-board | Grade - XI | Set - B
(i) 1-Chloro-2-nitro-4-methylbenzene
(ii) 1-Chloro-4-methyl-2-nitrobenzene
(iii) 2-Chloro-1-nitro-5-methylbenzene
(iv) m-Nitro-p-chlorotoluene
13 What is the other name for acyclic compounds? 1
(i) Aliphatic
(ii) Aromatic
(iii) Heterocyclic
(iv) Alicyclic
Question number 14-18 are Assertion and Reason type of questions
Each question consists of two statements, namely ,Assertion (A) and Reason (R).
For selecting the correct answer, use the following code:
(a) Both Assertion (A) and Reason (R) are the true and Reason (R) is a correct explanation of
Assertion (A).
(b) Both Assertion (A) and Reason (R) are the true but Reason (R) is not a correct explanation of
Assertion (A).
(c) Assertion (A) is true and Reason (R) is false.
(d) Assertion (A) is false and Reason (R) is true
Q. No Questions Marks
14 Assertion (A): Nodes are the region or spaces where there is no probability of 1
finding of electron.
Reason (R): 1s orbital has zero node, 2s has one node, 3s has 2 nodes.
15 Assertion (A): sodium chloride formed by the action of chlorine gas on sodium 1
metal is a stable compound.
Reason (R):This is because sodium and chloride ions acquire octet in sodium
chloride formation.
16 Assertion (A): NH3 (g) → NH3(l), ΔS = + ve. 1
Reason (R): Evaporation of water is endothermic but still spontaneous because
ΔS = +ve.
17 Assertion (A): Allylic free radical is more stable than simple free radical. 1
Reason (R): Allylic free radical is stabilized by resonance.
18 Assertion (A): Nitration of nitrobenzene mainly gives m-dinitrobenzene. 1
Reason (R): -NO2 group is electron donating group.
SECTION B
Q. No Questions Marks
19. Calculate the mole fraction of ethyl alcohol (C 2H5OH) and water in a solution in 2
which 46g of ethyl alcohol and 90g of water have been mixed.
Page 3 of 7 | Pre-board | Grade - XI | Set - B
OR
The density of nitric acid solution which is 63% by mass HNO3 is 1.41g/cm 3 .
What is the molarity of the solution?
20. Derive the relation CP & CV. 2
21 Arrange the following as instructed : 2
(a)F, Cl, Br, I (Increasing order of reactivity)
(b) s B, Al, Mg and K, ( decreasing order of their metallic character)
22 What is the KC for following equilibrium when concentration of each substance 2
is: SO2 = 0.60M, [O2] = 0.82 M and SO3 = 1.90 M 2SO2 + O2 2SO3
23 Explain the Diamagnetic nature of N2 on the basis of molecular orbital diagram. 2
24 Balance the following redox reaction : 2
MnO4–(aq) + SO2(g) → Mn2+(aq) + HSO4– (aq) (in acidic medium)
OR
Cr2O7 (aq) + SO2(g) → Cr (aq) + SO42-(aq) (in acidic medium)
2- 3+
25 (a)Draw the resonating structure of Chlorobenzene. 2
(b) Arrange the primary secondary and tertiary and methyl Carbon free radical
in decreasing order of stability.
SECTION C
Q. No Questions Marks
26 (a) State Heisenberg's Uncertainty Principle. 3
(b)What is the wavelength of light emitted when the electron in a hydrogen
atom undergoes transition from the energy level with n = 4 to n = 1?
27 (a)Draw the hydrogen bonded structure of (i) acetic acid (ii) o-nitrophenol. 2
(b)BeF2 molecule is linear while SF 2 is angular though both are triatomic.
Explain. 1
OR 3
Arrange the following in increasing order of the property indicated:
(a) H2O, H2S, BF3 (dipole moment)
(b) LiCl, LiBr, LiI (covalent character)
(c) NaBr, NaI, NaCl (melting point)
28 (a)Why is benzene extra-ordinarily stable though it contains three double 1
bonds?
(b) why odd number of alkanes cannot be prepared using wurtz reaction 2
29 (a) Write the conjugate acid and conjugate base of NH3. 3
(b) Calculate pH of a 1.0 × 10–8 M solution of HCl.
OR
Calculate the pH of 0.08 M solution of HOCl. The ionization constant of the
acid is 2.5 × 10–5. Determine the percent dissociation of HOCl.
Page 4 of 7 | Pre-board | Grade - XI | Set - B
30 Give one condition in which law of conservation of mass is not applicable. 1
Calcium carbonate reacts with aqueous HCl according to the reaction:
CaCO3 (s) + 2HCl (aq) CaCl2 (aq) + CO2 (g) + H2O(l) 2
What mass of CaCO3 is required to react completely with 25 mL of 0.75 M
HCl?
SECTION D
Q. No Questions Marks
31 Read the passage given below and answer the following questions: 4
Orbitals are regions or spaces where there is a maximum probability of finding
electrons. Qualitatively, these orbitals can be distinguished by their size, shape,
and orientation. An orbital of small size means there is more chance of finding
the electron near the nucleus. Shape and orientation mean the direction in which
the probability of finding the electron is maximum. Atomic orbitals can be
distinguished by quantum numbers. Each orbital is designated by three quantum
numbers n, l, and ml (magnetic quantum number) which define energy, shape,
and orientation but these are not sufficient to explain spectra of multi-electrons
atoms. Spin quantum number (ms) determines the spin of electrons. Spin angular
momentum of the electron has two orientations relative to the chosen axis which
are distinguished by spin quantum numbers ms which can take values +1/2 and –
1/2.
(a) what is the shape of f orbitals.
(b) Name two d-orbitals that are on-axis.
(c) Which of the following orbitals are degenerate?
3dxy, 4dxy, 3dz2, 3dyz, 4dyz, 4dz2
(d) state hunds rule of multiplicity.
Or
State Pauli’s exclusion principle.
32 Read the passage given below and answer the following questions: 4
Organic reactions can be classified into four main categories. Substitution
reactions, addition reactions, elimination reactions and rearrangement reactions.
Substitution reactions can be further classified into free radical, nucleophilic and
electrophilic substitution reactions. Addition reactions can be nucleophilic as
well as electrophilic addition reactions. Dehydration, dehydrohalogenation,
dehalogenation are examples of elimination reactions. Conversion by
ammonium cyanate to urea is an example of rearrangement reactions. Reactions
are classified on the basis to nature of intermediate species formed. Mechanism
of reaction is exact path followed by the reaction involving all steps showing
intermediates and slowest steps of the reaction which is rate determining step.
Oxidation, reduction, combustions reactions are also important in hydrocarbons.
(a) what is homolytic and hetrolytic fission?
(b) Which is a better nucleophile, – OH and HS– ?
(c)Give differences between inductive effect and resonance effect.
OR
Page 5 of 7 | Pre-board | Grade - XI | Set - B
Electromeric effect is a temporary effect. Assign reason.
SECTION E
Q. No Questions Marks
33 (a) State the hess law of constant heat summation. 1
(b)For the reaction, 2Cl (g) Cl2 (g), what are the signs of H and S? 1
(c) The value of ΔfH° for NH3 is –91.8 kJ mol–1. Calculate enthalpy change for 1
the following reaction: 2NH3(g) → N2(g) + 3H2(g)
(d)Calculate the enthalpy of formation of methane, given that the enthalpies of 2
combustion of methane, graphite and hydrogen are -890.2 kJ, -393.4 kJ and
-285.7 kJ/mol respectively.
OR
(a)Write the expression of work done for a 1 mole of an ideal gas for the 2
different cases mentioned here :
(i) For an irreversible expansion of the gas from V1 to V2.
(ii) For reversible isothermal expansion of the gas from V1 to V2.
(iii) For expansion of the gas into an evacuated vessel.
(iv) For adiabatic expansion resulting into change of temperature from T1 to T2.
(b) Write the conditions in terms of ΔH and ΔS when a reaction would be 1
always spontaneous.
(c)For the reaction at 298 K, 2A + B C, H = 400 kJ mol–1 and S = 0.2 kJ 2
K–1 mol–1 At what temperature will the reaction become spontaneous
considering H and S to be constant over the temperature range?
34 (a) Benzyl carbocation is more stable than ethyl carbocation. Justify. 1
(b) Which is expected to be more stable, O2NCH2CH2O– or CH3CH2O– and 1
why?
(c) Draw the structure of 3-Hydroxy-4-methylpent-4-ene-1-nitrile. 1
(d) Write the principle involved in given separation technique: 2
(i) Chromatography (ii) Fractional distillation.
OR 1
(a) Draw the structure of 2-Chloro-3-ethylpentan-1,4-diene.
1
(b) Write the difference between the electrophile & nucleophile.
(c) Consider structures (I) to (VI) and answer the questions:
3
(i) Which of the above compounds from pairs of metamers?
(ii) Identify the pairs of compounds which are functional group isomers.
(iii) Identity the pairs of compounds that represents position isomerism.
Page 6 of 7 | Pre-board | Grade - XI | Set - B
35 (a) Write one chemical equation each to illustrate the following reactions 2
(i) Friedel—Crafts alkylation
(ii) Decarboxylation
(b) An alkene 'A' on ozonolysis gives a mixture of benzaldehyde and butan-2- 2
one. Write structure and IUPAC name of 'A'.
(c)Give one chemical test to distinguish between ethane and ethene. 1
OR
2
(a) Give mechanism of the following reaction :
(b) Carry out the following conversions : 3
(i) Benzene to acetophenone
(ii) Ethanoic acid to methane
(iii) Propyne to propanone
Page 7 of 7 | Pre-board | Grade - XI | Set - B
