Board Paper of Class 12-Science 2011 Chemistry (SET 3) - Solutions
(i) All questions are compulsory
(ii) Question numbers 1 to 8 are very short-answer questions and carry 1 mark each.
(iii) Question numbers 9 to 18 are short-answer questions and carry 2 marks each.
(iv) Question numbers 19 to 27 are also short-answer questions and carry 3 marks.
(v) Question numbers 28 to 30 are long-answer questions and carry 5 marks each.
(vi) Use Log Tables, if necessary. Use of calculators is not allowed.
- Question 1
Define ‘activation energy’ of a reaction.VIEW SOLUTION
- Question 2
What is meant by ‘reverse osmosis’?VIEW SOLUTION
- Question 3
What type of ores can be concentrated by magnetic separation method?VIEW SOLUTION
- Question 4
Write the IUPAC name of the following compound: CH2 = CHCH2BrVIEW SOLUTION
- Question 5
What is meant by ‘lanthanoid contraction’?VIEW SOLUTION
- Question 6
How would you convert ethanol to ethene?VIEW SOLUTION
- Question 7
Draw the structure of 4-chloropentan-2-one.VIEW SOLUTION
- Question 8
Give a chemical test to distinguish between ethylamine and aniline.VIEW SOLUTION
- Question 9
Calculate the packing efficiency of a metal crystal for a simple cubic lattice.VIEW SOLUTION
- Question 10
Explain how you can determine the atomic mass of an unknown metal if you know its mass density and the dimensions of unit cell of its crystal.VIEW SOLUTION
- Question 11
Differentiate between molarity and molality values for a solution. What is the effect of change in temperature on molarity and molality values?VIEW SOLUTION
- Question 12
The thermal decomposition of HCO2H is a first order reaction with a rate constant of 2.4 × 10−3 s−1 at a certain temperature. Calculate how long will it take for three-fourths of initial quantity of HCO2H to decompose.
(log 0.25 = − 0.6021)VIEW SOLUTION
- Question 13
What do you understand by the rate law and rate constant of a reaction?
Identify the order of a reaction if the units of its rate constant are:
(i) L−1 mol s−1
(ii) L mol−1 s−1VIEW SOLUTION
- Question 14
Describe the principle controlling each of the following processes:
(i) Preparation of cast iron form pig iron.
(ii) Preparation of pure alumina (Al2O3) from bauxite ore.VIEW SOLUTION
- Question 15
Explain giving reasons:
(i) Transition metals and their compounds generally exhibit a paramagnetic behaviour.
(ii) The chemistry of actinoids is not so smooth as that of lanthanoids.VIEW SOLUTION
- Question 16
Complete the following chemical equations:
State reasons for the following:
(i) Cu (I) ion is not stable in an aqueous solution.
(ii) Unlike Cr3+, Mn2+, Fe3+ and the subsequent other M2+ ions of the 3d series of elements, the 4d and the 5d series metals generally do not form stable cationic species.VIEW SOLUTION
- Question 17
Write the main structural difference between DNA and RNA. Of the four bases, name those which are common to both DNA and RNA.VIEW SOLUTION
- Question 18
Write such reactions and facts about glucose which cannot be explained by its open chain structure.VIEW SOLUTION
- Question 19
A solution prepared by dissolving 8.95 mg of a gene fragment in 35.0 mL of water has an osmotic pressure of 0.335 torr at 25°C.
Assuming that the gene fragment is a non-electrolyte, calculate its molar mass.VIEW SOLUTION
- Question 20
Classify colloids where the dispersion medium is water. State their characteristics and write an example of each of these classes.
Explain what is observed when
(i) an electric current is passed through a sol
(ii) a beam of light is passed through a sol
(iii) an electrolyte (say NaCl) is added to ferric hydroxide solVIEW SOLUTION
- Question 21
How would you account for the following:
(i) NF3 is an exothermic compound but NCl3 is not.
(ii) The acidic strength of compounds increases in the order:
PH3 < H2S < HCl
(iii) SF6 is kinetically inert.
- Question 22
Write the state of hybridization, the shape and the magnetic behaviour of the following complex entities:
(i) [Cr(NH3)4 Cl2] Cl
(ii) [Co(en)3] Cl3
(iii) K2 [Ni(CN)4]VIEW SOLUTION
- Question 23
State reasons for the following:
(i) pKb value for aniline is more than that for methylamine.
(ii) Ethylamine is soluble in water whereas aniline is not soluble in water.
(iii) Primary amines have higher boiling points than tertiary amines.VIEW SOLUTION
- Question 24
Rearrange the compounds of each of the following sets in order of reactivity towards SN2 displacement:
(i) 2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane
(ii) 1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 3-Bromo-2-methylbutane
(iii) 1-Bromobutane, 1-Bromo-2, 2-dimethylpropane, 1-Bromo-2-methylbutaneVIEW SOLUTION
- Question 25
How would you obtain the following:
(i) Benzoquinone from phenol
(ii) 2-methyl propan-2-ol from methyl-magnesium bromide
(iii) Propane-2-ol from propeneVIEW SOLUTION
- Question 26
Write the names and structures of the monomers of the following polymers:
(iii) NeopreneVIEW SOLUTION
- Question 27
What are the following substances? Give one example of each.
(i) Food preservatives
(ii) Synthetic detergents
(iii) AntacidsVIEW SOLUTION
- Question 28
(a) Draw the structures of the following molecules:
(b) Complete the following chemical equations:
(i) HgCl2 + PH3 →
(ii) SO3 + H2SO4 →
(iii) XeF4 + H2O →
(a) What happens when
(i) chlorine gas is passed through a hot concentrated solution of NaOH?
(ii) sulphur dioxide gas is passed through an aqueous solution of a Fe (III) salt?
(b) Answer the following:
(i) What is the basicity of H3PO3 and why?
(ii) Why does fluorine not play the role of a central atom in inter-halogen compounds?
(iii) Why do noble gases have very low boiling points?VIEW SOLUTION
- Question 29
(a) What type of a battery is lead storage battery? Write the anode and cathode reactions and the overall cell reaction occurring in the operation of a lead storage battery.
(b) Calculate the potential for half-cell containing 0.10 M K2Cr2O7 (aq), 0.20 M Cr3+ (aq) and 1.0 × 10−4 M H+ (aq)
The half-cell reaction is and the standard electrode potential is given as E0 = 1.33 V.
(a) How many moles of mercury will be produced by electrolysing 1.0 M
Hg (NO3)2 solution with a current of 2.00 A for 3 hours?
[Hg(NO3)2 = 200.6 g mol−1]
(b) A voltaic cell is set up at 25°C with the following half-cells Al3+ (0.001 M) and Ni2+ (0.50 M). Write an equation for the reaction that occurs when the cell generates an electric current and determine the cell potential.
- Question 30
(a) Illustrate the following name reactions:
(i) Cannizzaro’s reaction
(ii) Clemmensen reduction
(b) How would you obtain the following:
(i) But-2-enal from ethanal
(ii) Butanoic acid from butanol
(iii) Benzoic acid from ethylbenzene
(a) Given chemical tests to distinguish between the following:
(i) Benzoic acid and ethyl benzoate
(ii) Benzaldehyde and acetophenone
(b) Complete each synthesis by giving missing reagents or products in the following: