BRAINWARE UNIVERSITY
MODEL QUESTION FOR HIGHER SECONDARY (WBCHSE)
SUBJECT: CHEMISTRY
FULL MARKS: 70 TIME: 3 HOURS
[Special credit will be given to the answers which are brief and to the point. The figure in the
margin indicates full marks. Marks will be deducted for spelling mistakes, untidiness and bad
handwriting. Figures in the margin indicate full marks for question]
General Instructions:
Read the following instructions carefully.
(a) There are 35 questions in this question paper with internal choice.
(b) SECTION A consists of 14 multiple -choice questions carrying 1 mark each.
(c) SECTION B consists of 4 very short answer questions carrying 1 marks each.
(d) SECTION C consists of 5 short answer questions carrying 2 marks each.
(e) SECTION D consists of 9 short answer questions carrying 3 marks each.
(f) SECTION E consists of 3 long answer questions carrying 5 marks each.
(g) All questions are compulsory.
(h) Use of log tables and calculators is not allowed.
SECTION A
1 × 14 = 14
The following questions are multiple -choice questions with one correct answer. Each question
carries 1 mark. There is no internal choice in this section.
1. Which of the following solutions will have the highest conductivity at 298 K?
(a) 0.01 M HCl solution (b) 0.1 M HCl solution
(c) 0.01 M CH 3COOH solution (d) 0.1 M CH 3COOH solution
2. Identify ‘X’ in the reaction given below.
a) CrO3 b) CrO2Cl2
c) Alkaline KmnO4 d) Anhydrous AlCl3
3. The vitamins which can be stored in our body are:
(a) Vitamin A, B, D and E (b) Vitamin A, C, D and K
© Vitamin A, B, C and D (d) Vitamin A, D, E and K
4. What is IUPAC name of the ketone A, which undergoes iodoform reaction to give
CH3CH= C(CH3)COONa and yellow precipitate of CHI3?
(a) 3-Methylpent-3-en-2one (b) 3-Methylbut-2-en- one
(c) 2, 3-Dimethylethanone (d) 3-Methylpent-4-one
5. Which of the following is not correct?
(a) In haloarenes, the electron pairs on halogen atom are in conjugation with π-electrons of the ring.
(b) The carbon-magnesium bond is covalent and non-polar in nature.
(c) During SN1 reaction, the carbocation formed in the slow step being sp2 hybridised is planar.
(d) Out of CH2= CH-Cl and C6H5CH2Cl, C6H5CH2Cl is more reactive towards SN1 reaction
6. Amorphous solid can also be called
(a) pseudo solid (b) True solid
(c) super cooled solid (d) Super cooled solid
7. Which of the following statement is true?
(a) molecularity of reaction can be zero or a fraction.
(b) molecularity has no meaning for complex reactions.
(c) molecularity of a reaction is an experimental quantity
(d) reactions with the molecularity three are very rare but are fast.
8. Which anion can undergo both oxidation and reduction
(a) Cr2O72- (b) NO3-
(c) Ocl- (d) S2-
9. Which of the following observation is shown by 2 -phenyl ethanol with Lucas Reagent?
(a) Turbidity will be observed within five minutes
(b) No turbidity will be observed
(c) Turbidity will be observed immediately
(d) Turbidity will be observed at room temperature but will disappear after five minutes.
10. What is the coordination number of chromium in K3[Cr(C2O4)3]?
(a) 1 (b) 2
(c) 3 (d) 6
11. Which of the following condition is not satisfied by an ideal solution?
(a) ΔHmixing = 0 (b) ΔVmixing = 0
(c) Raoult’s Law is obeyed (d) Formation of an azeotropic mixture
12. Which of the following forces is involved in physical adsorption?
(a) Gravitational force (b) Magnetic force
(c) Van der Waals force (d) Electromagnetic force
13. Which of the following is not a vinylic alcohol?
(a) CH2=CH-OH (b) HO-CH=CH-CH3
(c) CH2=CH-CH2-OH (d) CH3-CH2-CH=CH-OH
14. Products formed when Nitrobenzene reacts with HNO3/H2SO4 at 80-100°C
(a) 1, 4-Dinitrobenzene (b) 1, 2, 4-Trinitrobenzene
(b) 1, 2-Dinitrobenzene (d) 1, 3-Dinitrobenzene
SECTION B
This section contains 4 questions with internal choice in one question. The following questions are
very short answer type and carry 1 marks each.
1×4=4
1. Why does the conductivity of a solution decrease with dilution?
Or
Suggest two materials other than hydrogen that can be used as fuels in the fuel cells.
2. For a reaction R → P, half-life (t1/2) is observed to be independent of the initial concentration
of reactants. What is the order of reaction?
3. Physisorption is reversible while chemisorption is irreversible. Why?
4. Give IUPAC name of ionization isomer of [Ni(NH3)3NO3] Cl.
Or
Write the formula for the following coordination compounds:
(i)Tetraamminediaquacobalt(IlI) chloride
SECTION C
This section contains 5 questions with internal choice in one question. The following questions are
short answer type and carry 2 marks each.
5 × 2 = 10
1. A 1.00 molal aqueous solution of trichloroacetic acid (CCl3COOH) is heated to its boiling
point. The solution has the boiling point of 100.18°C. Determine the van’t Hoff factor for
trichloroacetic acid. (Kb for water = 0.512 K kg mol-1) .
Or
What is meant by ‘reverse osmosis’?
2. Explain how temperature affects the extent of physical and chemical adsorption.
Or
Define ‘peptization’.
3. Why does NO2 dimerise?
Or
Draw the structure of XeF2 molecule.
4. Describe the shape and magnetic behaviour of following complexes :
(i) [CO(NH3)6]3+
(ii) [Ni(CN)4]2- (At. No. Co = 27, Ni = 28)
5. Write the structure of the product obtained when glucose is oxidised with nitric acid.
SECTION D
This section contains 9 questions with internal choice in one question. The following questions are
short answer type and carry 3 marks each.
(9× 3 = 27)
1. Answer the following questions:
(a) What makes liquid and gases fluids?
(b) In a bcc unit cell, how many atoms per unit cell (z) are there?
(c) Explain Schottky Defect.
Or
(d) Classify the following solids on the nature of intermolecular forces: Benzene, Silver
(e) Give the reason why AgCl shows Frenkel defect while NaCl does not.
(f) What type of semiconductor will be formed when Ge is doped with Al?
(1+1+1)
2. (a) How much charge is required for the reduction of 1 mole of Zn+2 to Zn?
(b)The rate constants of a reaction at 200K and 500K are 0.02s–1 and 0.20s–1 respectively.
Calculate the value of Ea (Given 2.303R = 19.15 JK -1mol-1).
Or
(a)Define conductivity and molar conductivity in an electrolyte solution.
(b) Discuss how they vary as the temperature changes.
(1+2)
3. (a) Aldehydes and Ketones have lower boiling points than corresponding alcohols. Why ?
(b) You are given four organic compounds “A”, “B”, “C” and “D”. The compounds “A”, “B” and “C”
form an orange- red precipitate with 2,4 DNP reagent. Compounds “A” and “B” reduce Tollen’s
reagent while compounds “C” and “D” do not. Both “B” and “C” give a yellow precipitate when
heated with iodine in the presence of NaOH. Compound “D” gives brisk effervescence with
sodium bicarbonate solution. Identify “A”, “B”, “C” and “D” given the number of carbon atoms in
three of these carbon compounds is three while one has two carbon atoms. Give an explanation
for y our answer. (1+2)
4. Which alkyl halide from the following pair is (i) Chiral and (ii) undergoes SN1 reaction faster?
(a) (CH3)2CBr
(b) CH3CH2CHBrCH3
Or
Which compound in each of the following pairs will react faster in SN2 reaction with —OH?
(i) CH3Br or CH3I (ii) (CH3)3 CCl or CH3Cl (2×1.5)
5. Identify A, B and C in the following reactions :
Or
Arrange the following in increasing order of their basic strength in aqueous solution: CH3.NH2,
(CH3)3N, (CH3)2NH.
How are the following conversions carried out?
(i) Propene to Propan-2-ol
(ii) Ethyl chloride to Ethanal (2×1.5)
6. For the cell Zn(s) | Zn2+(2M) | | Cu2+(0.5 M) | Cu(s)
(a) Write equation for each half-reaction.
(b) Calculate the cell potential at 25 °C.
[Given: EZn2+/Zn= – 0.76 V; ECu2+/Cu= + 0 .34V] (1+2)
Or
(a) Calculate ΔrG0 for the reaction
Mg (s) + Cu2+ (aq) → Mg2+ (aq) + Cu (s)
Given : E0cell = + 2.71 V, 1 F = 96500 C mol-1
(b) Name the type of cell which was used in Apollo space programme for providing electrical
power. (2+1)
7. Define osmotic pressure. One mole of table salt is dissolved in one litre of water. At a
temperature of 27ºC, what would be the osmotic temperature of this solution? (1+2)
8. What are lyophobic colloids? Give one example for them. What is the difference between
physisorption and chemisorption? (1+1+1)
9. (a) Define rate constant.
(b)The thermal decomposition of HCO2H is a first order reaction with a rate constant of 2.4 × 10-
3 -1
s at a certain temperature. Calculate how long will it take for three-fourths of initial quantity
of HCO2 H to decompose. (log 0.25 = -0.6021). (1+2)
SECTION E
This section contains 3 questions with internal choice in one question. The following questions are
long answer type and carry 5 marks each.
(5× 3 = 15)
1. (a) Define ‘order of a reaction’.
(b) Activation energy of a reaction.
(c) first order reaction takes 20 minutes for 25% decomposition. Calculate the time when 75%
of the reaction will be completed.
(Given: log 2 = 0.3010, log 3 = 0.4771, log 4 = 0.6021) (1+2+2)
or
(a) Write the unit of rate constant for a zero order reaction.
(b) Distinguish between ‘rate expression’ and ‘rate constant’ of a reaction.
(c) The rate constant for a reaction of zero order in A is 0.0030 mol L-1 s-1. How long will it take
for the initial concentration of A to fall from 0.10 M to 0.075 M?
(1+2+2)
2. Explain:
(a) Helium does not form chemical compounds.
(b) Bond dissociation energy of fluorine is less than that of chlorine.
(c) Two S-O bonds in SO2 are identical. (1+2+2)
3. (a) State and illustrate the following:
(i) Wolff-Kishner reduction
(ii) Aldol condensation
(b) Formaldehyde does not take part in Aldol condensation. Why ?
(c) An organic compound (A) which has characteristic odour, on treatment with NaOH forms
two compounds (B) and (C). Compound (B) has the molecular formula C7H8O which on
oxidation with CrO3 gives back compound (A). Compound (C) is the sodium salt of the acid.
Compound (C) when heated with soda lime yields an aromatic hydrocarbon (D). Deduce the
structures of (A), (B), (C) and (d) Write chemical equations for all reactions taking place.
(1+1+1 +2)
Or
(a) What is Tollen’s reagent?
(b) Arrange the following compounds in an increasing order of their reactivity in nucleophilic
addition reactions: ethanal, propanal, propanone, butanone.
(c) Give a chemical test to distinguish between Propanal and Propanone.
(d) Give chemical tests to distinguish between
(i) Phenol and Benzoic acid (ii) Benzophenone and Acetophenone
(1+1+1 +2)
