Class 12 Sample Paper Chemistry (Half Yearly)

SAMPLE
PAPER
Half Yearly Examination

Prepared For
NCERT BASED SYLLABUS
Applicable For
CBSE BOARD AND STATE BOARD USING NCERT

WWW.

CHEMISTRY
Time – 3 hrs. Class – XII M.M. : 70
Date – 14.09.2022 (Wednesday)
Name of the student _________________________________________________ Section _____

GENERAL INSTRUCTIONS:
• All questions are compulsory.
• Question nos. 1 to 21 are MCQs with one
correct option and carrying 1 mark each.
• Question nos. 22 to 24 are objective/short
answer type questions.
• Question nos. 25 to 28 are of 2 marks each.
• Question nos. 29 to 32 is of 3 marks each.
• Question nos. 33 to 35 is of 5 marks each.

SECTION - A
Q. 1 to 21 is of 1 mark each.
Q.1 Which of the following aqueous solution should have highest boiling point ?
a) 1 M NaOH b) 1 M Na2SO4 c) 1M NH4NO3 d) 1 M KNO3
Q.2 Which of the following statement is false ?
a) Two different solution of sucrose of same molality prepare in different solvent will
have the same depression in freezing point.
b) The osmotic pressure of a solution is given by the equation π=CRT. (where C is the
molarity of the solution)
c) Decreasing order of osmotic pressure for 0.01M aqueous solution of Barium Chloride,
Potassium chloride, acetic acid and sucrose is BaCl2 > KCl > CH3COOH > Sucrose
d) According to Raoult’s Law, the vapour pressure exeterd by a volatile component of
solution is directly proportional to its molar fraction in the solution.
Q.3 We have three aqueous solution of NaCl labelled as ‘A’, ‘B’ and ‘C’ with concentration 0.1
M, 0.01 M and 0.001 M respectively. The value of Van’t Hoff factor for these solution will
be in the order-
a) iA < iB < iC a) iA > iB > iC a) iA = iB = iC a) iA < iB > iC
Q.4 On the basis of the information given below mark the correct options –
i) In bromoethane and chloroethane mixture intermolecular interaction of A-A and B-B
type are nearly same as A-B type interaction.
ii) In the ethanol and acetone mixture A-A or B-B type intermolecular interactions are
stronger than A-B type interaction.
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iii) In chloroform and acetone mixture A-A or B-B type intermolecular interactions are
weaker than A-B type interaction
a) solution (ii) and (iii) will follow Raoult’s law
b) solution (i) will follow Raoult’s law
c) solution (ii) will show negative deviation from Raoult’s law
d) solution (iii) will show positive deviation from Raoult’s law
Q.5 KH valves for Ar(g), CO2(g), HCHO(g) and CH4(g) are 40.39, 1.67, 1.83 × 10-5 and 0.413
respectively. Arrange these gases in the order of their increasing solubility.
a) HCHO < CH4 < CO2 < Ar b) HCHO < CO2 < CH4< Ar
c) Ar < CO2 < CH4< HCHO b) Ar < CH4 < CO2 < HCHO
Q.6 Use the data given below, find out which of the following is the strongest oxidizing agent.

E 0 Cr2 O72− / Cr 3+ =1.33V E 0 Cl2 / Cl − =1.36V

E 0 MnO4− / Mn 2+ =1.51V E 0 Cr 3+ / Cr = −0.74V
a) Cl − b) Mn2+ c) MnO4− d) Cr3+

Q.7 The quantity of charge required to obtain 1 mole of Aluminium from Al2O3 is –
a) 1 F b) 6 F c) 3 F d) 2 F
Q.8 While charging the lead storage battery –
a) PbSO4 anode is reduced to Pb b) PbSO4 cathode is reduced to Pb
c) PbSO4 cathode is oxidized to Pb d) PbSO4 anode is oxidized to Pb

Q.9 ∧ 0 M (NH4OH) is equal to –

a) ∧ 0 M (NH4OH) + ∧ 0 M (NH4Cl) - ∧ 0 M (HCl) b) ∧ 0 M (NH4Cl) + ∧ 0 M (NaOH) - ∧ 0 M (NaCl)

c) ∧ 0 M (NH4Cl) + ∧ 0 M (NaCl) - ∧ 0 M (NaOH) d) ∧ 0 M (NaOH) + ∧ 0 M (NaCl) - ∧ 0 M (NH4Cl)
Q.10 Consider a first order gas phase decomposition reaction given below –
A(g) → B(g) + C(g)
The initial pressure of the system before decomposition of A was Pi. After lapse of time ‘t’,
total pressure of the system increased by x unit and become ‘Pt’. The rate constant ‘K’ for
the reaction is given as –

2.303  P  2.303  Pi 
a) K = log  i  b) K = log  
t  pi − x  t  2 pi − Pt 

2.303  Pi  2.303  P 
c) K = log   d) K = log  i 
t  2 pi + Pt  t  pi + x 

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Q.11 Consider the Arrhenius equation given below and mark the correct option.
K = Ae-Ea/RT
a) Rate constant increase exponentially with increasing activation energy and decreasing
temperature.
b) Rate constant decrease exponentially with increasing activation energy and decreasing
temperature.
c) Rate constant increase exponentially with decreasing activation energy and decreasing
temperature.
d) Rate constant increase exponentially with decreasing activation energy and increasing
temperature.
Q.12 Which of the following expression is correct for the rate of reaction given below –
5 Br − (aq ) + BrO3− (aq ) + 6 H + → 3Br2 ( g ) + 3H 2O(l )

a)
[ ]
∆ Br −
=5
∆ H+ [ ] b)
[ ]
∆ Br −
=
[ ]
6 ∆ H+
∆t ∆t ∆t 5 ∆t

c)
[ ]
∆ Br −
=
5 ∆ H+ [ ] d)
[ ]
∆ Br −
=6
[ ]
∆ H+
∆t 6 ∆t ∆t ∆t
Q.13 A first order reaction is 50% completed in 1.26×1014 sec. How much time would it takes
for 100% completion ?
a) 1.26×1015 sec b) 2.52×1025 sec c) 2.52×1014 sec d) Infinite
Q.14 On addition of small amount of KMnO4 to connected H2SO4 a green oily compound is
obtained which is highly explosive in nature. Identify the compound from the following :
a) Mn2O7 b) MnO2 c) MnSO4 d) Mn2O3
Q.15 Which of the following are not disproportionation reactions ?
1. Cu+ (aq) → Cu2+ (aq) + Cu(s)
2. 3MnO4− + 4 H + → 2MnO4− + MnO2 + 2 H 2O
3. 2KMnO4 → K2MnO4 + MnO2 + O2
4. 2 MnO4− + 3Mn2+ + 2H2O → 5MnO2 + 4 H +
a) 1 & 3 b) 1, 2, & 3 c) 2, 3, 4 d) 1 & 4
Q.16 Gadolinium belong to 4f-series. It's atomic number is 64. Which of the following is correct
electronic configuration of gadolinium ?
a) [Xe] 4f75d16s2 b) [Xe] 4f65d26s2 c) [Xe] 4f86d2 d) [Xe] 4f95s1
Q.17 Why HCl not used to make the medium acidic in oxidation reaction of KMnO4 in acidic
medium ?
a) Both HCl and KMnO4 act as oxidising agents.
b) KMnO4 oxidises HCl into Cl2 which is also an oxidising agent.
c) KMnO4 is weaker oxidising agent than HCl
d) KMnO4 act as reducing agent in the presence of HCl.
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Q.18 When 1 mole of CrCl3.6H2O is treated with excess of AgNO3, 3 mole of AgCl are obtained.
The formula of the complex is -
a) [CrCl3(H2O)3].3H2O b) [CrCl(H2O)5]Cl2.H2O
c) [CrCl2(H2O)4]Cl.2H2O d) [Cr(H2O)6]Cl3
Q.19 Indicate the complex ion which shows Geometrical Isomexism.
a) [Cr(H2O)4Cl2]+ b) [Co(NH3)6]3+ c) [Pt(NH3)3Cl] d) [Cr(CN)5(NC)]3-
Q.20 What kind of isomerism exist between [Cr(H2O)6]Cl3 (violet) and [Cr(H2O)5Cl]Cl2.H2O
(greyish-Green)
a) Linkage isomerism b) Ionisation Isomerism
c) Hydrate isomerism d) Coordination Isomerism
Q.21 IUPAC name of [Pt(NH3)2Cl (NO2)] is
a) Platinum diaminechloronitrite b) Chloronitrito-N-ammineplatinum (II)
c) Diamminechlorido nitrito-N-platinum (II) d) Diammine chlorido nitrito-N-Platinate(II)
Q.22 Fill in the blanks. (1x4=4)
a) The coordination number of the central atom in [Cr(en)3]3+ is ____________
b) The oxidation number of Cr in CrO5 is ____________
c) The order of the reaction H2+Cl2 → 2HCl is ____________
d) The electrolyte used for primary cell (Dry cell) is ____________
Q.23 Match the following. (1x6=6)
A B
a) Ebulioscopic constant i) High efficiency
b) Cryoscopic constant ii) CrO3
c) Rusting of Iron iii) Fe2O3
d) Fuel cell iv) Elevation in boiling point
e) Acidic oxide v) Mn2O7
f) Amphoteric oxide vi) Electrochemical process
vii) Depression in freezing point
viii) Osmotic pressure
ix) Primary cell
Q.24 Define the following – (1x4=4)
a) Activation energy b) Pseudo first order reaction
c) Ambidentate ligand e) Ionisation isomers

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SECTION - B
Q.25 to 28 is of 2 marks each.
Q.25 Write the geometrical isomers of the compound [Cr(NH3)4Cl2]+ will they show optical
isomerism. Justify your answer ?
Q.26 Draw the shape of following ions.
a) CrO4−2 b) Cr2 O7−2 c) MnO4− d) MnO4−2
Q.27 a) Draw a graph for log A vs t for a 1st order reaction (A → product)
b) Draw a graph for t1/2 vs [A0] for a zero order reaction.
Q.28 Define the following -
a) Osmotic pressure b) Anoxia
SECTION – C
Q.29 to 32 is of 3 marks each.
Q.29 Write IUPAC name of the following -
a) [Co(NH3)5 (ONO)]2+ b) K3[Cr(C2O4)3] c) [Fe(NH3)4 Cl (NO2)]Cl
Q.30 a) Why mercury cell gives constant voltage throughout its life? Explain with reactions.
b) How many columbs of electricity is required for the following 20gm Ca from Ca2+
ions. (Ca = 40)
Q.31 a) State and explain Kohlrausch's law with a suitable example.
b) What is 'Sacrificial electrode'? Explain with an example.
Q.32 Calculate log Kc for the reaction at 298 K and also ∆G0.
Cu(s) + 2Ag+(aq) → Cu2+ (aq) + 2Ag(s)
(given E 0 Ag / Ag = 0.80V and E 0 Cu / Cu = 0.34V )
+ 2+

SECTION – D
Q.33 a) What mass of NaCl (MW = 58.5 gm) must be dissolved in 65 gm of water to lower the
freezing point by 7.50C (Kf = 1.86 K kg mole-1) (i for NaCl = 1.87) (2½)
b) In a solvent 50% of an acid HA dimerises and rest dissociates. What is the Vant Hoff
factor of acid? (2½)
OR
a) A solution contains 0.8960 gm of K2SO4 (MW=174) in 500 m of solution. Its osmotic
pressure is found to be 0.69 atm. at 270C. Calculate the value of Van't Hoff factor. (2)
b) A solution containing 15 gm urea (MW=60) per litre of solution in water has same
osmotic pressure as a solution of glucose (MW=180) in water calculate the mass of
glucose present in one litre of its solution. (2)
c) What is edema ? (1)

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Q.34 a) A time required for 10% completion of a 1st order reaction at 300K is equal to that
required for its 25% completion at 310K. If the value of A is 4×1010 s-1. Calculate log K
at 320K and Ea. (log 3 = 0.4771, log2 = 0.3010, log2.73 = 0.436) (3)
b) Answer the following. (2)
i) Give an example of fractional order reaction.
ii) Rate determing step of a reaction.
OR
The following data were obtained during the 1st order thermal decomposition of SO2Cl2
at a constant volume - (2½)
SO2Cl2(g) → SO2(g) + Cl2(g)
Expt. (Time/sec) Total pressure (in atm.)
1. 0 0.5
2 100 0.6
Calculate the rate of reaction when total pressure is 0.65 atm. (log 5 = 0.6990, log 4 =
0.6021)
b) The decomposition of A → product has a value of K as 4.5×103 s-1 at 100C and energy of
activation 60 KJ/mole. At what temperature would K be 1.5×104 s-1. (2½)
Q.35 Give reason for the following -
a) (i) Cobalt (II) is stable in aqueous solution but in the pressure of complexing reagent it is
easily oxidised. (3)
(ii) Cr+2 is strongly reducing while Mn+3 is strongly oxidising.
(iii) ∆a H of transition metal is very high.
b) Write balance chemical reaction of the following- (2)
i) Cr2O7−2 + I − → (In acid medium)

ii) MnO4− + C 2O4−2 → (In acid medium)
OR
Give reason for the following. (1x5=5)
a) A transition metal exhibits highest oxidation states in oxides and fluorides.
b) The atomic size of Zr and Hf is almost same.
c) Among all the 1st row transition elements only E 0 Cu 2 + / Cu is +ve
d) Complete and balance the following equation –
(i) MnO4− + SO2 → (In acid medium)
(ii) MnO4− + I − + H 2O →

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