CHEMISTRY

PAPER – 1

(THEORY)

Question 1

(a) Fill in the blanks by choosing the appropriate word/words from those given in the brackets:
(increases, decreases, efficient, same as, 68, non-efficient, greater than, 74, less than, sp3d3, sp3d2, octahedral, distorted octahedral, remains same) [4×1]
(i) Both ccp and hcp are ____________ close packing and occupy about_________% of the available space.
(ii) The molar conductance of a solution _______________ with dilution, while its specific conductance _______________ with dilution.
(iii) The geometry of XeF6 molecule is _____________ and the hybridization of Xe atom in the molecule is _______________.
(iv) The acidic strength of phenol is ____________ ethyl alcohol but __________ nitro phenol.
(b) Complete the following statements by selecting the correct alternative from the choices given: [5] [4×1]
(i) The molal freezing point constant of water is 1·86 K kg mol-1. Therefore, the freezing point of 0·1M NaCl solution in water is expected to be:
(1) -1·86oC
(2) -0·372oC
(3) -0·186oC
(4) +0·372oC
(ii) Which among the following reacts fastest by SN2 reaction:
(1) (CH3)3C – Br
(2) (CH3)2CH Br
(3) CH3 – CH2 – Br
(4) CH3 – Br
(iii) When acetaldehyde is treated with Grignard reagent followed by hydrolysis, the product formed is:
(1) Primary alcohol
(2) Secondary alcohol
(3) Carboxylic acid
(4) Tertiary alcohol
(iv) Which of the following ores can be concentrated by froth floatation process:
(1) Haematite
(2) Calamine
(3) Zinc blende
(4) Bauxite
(c) Match the following: [4×1]
(i) Disaccharide (a) Adsorption
(ii) Arrhenius equation (b) Condensation polymer
(iii) Dacron (c) Activation energy
(iv) Freundlich isotherm (d) Sucrose
(d) Answer the following questions: [4×2]
(i) Calculate the mass of compound (molar mass = 256 g mol-1) to be dissolved in 75 g of benzene to lower its freezing point by 0·48 K (Kf = 5·12 K kg mol-1).
(ii) Write the IUPAC name of the complex [Cr(NH3)4Cl2]+. Which type of isomerism will be exhibited by it?
(iii) Why do the transition elements have higher enthalpies of atomisation? In 3d series (Sc to Zn), which element has the lowest enthalpy of atomisation and why?
(iv) Write balanced chemical equations for Carbylamine reaction and Diazotization reaction.

Question 2     [2]
(a) Identify the reaction order from each of the following rate constants:
(i) k = 2·3 × 10-5 L mol-1 s-1.
(ii) k = 3 ×10-4 s-1.

OR

(b) Write two differences between ‘order of reaction’ and ‘molecularity of reaction’.

Question 3 [2]
(a) Differentiate between an antiseptic and a disinfectant.
(b) Name a biodegradable detergent.

Question 4 [2]
What will be the major product obtained when 2-bromobutane reacts with alcoholic potassium
hydroxide? State the type of reaction involved in it.

Question 5     [2]
 Write the names of the monomers of the following polymers:
 (a) Nylon-6
 (b) Buna-N

Question 6    [2]
 Explain the amphoteric behaviour of amino acids.

Question 7 [2]
(a) How is phenol converted to benzoic acid? Explain with the help of balanced chemical
equations.

OR

(b) Write the mechanism of acid dehydration of ethanol to yield ethene.

Question 8 [2]

A substance decomposes by following first order kinetics. If 50% of the compound is
decomposed in 120 minutes, how long will it take for 90% of the compound to
decompose?

Question 9 [3]
 (a) Calculate the amount of CaCl2 (molar mass = 111 g mol-1) which must be added to 500 g
of water to lower its freezing point by 2 K, assuming CaCl2 is completely dissociated.
(Kf for water = 1.86 K kg mol-1).

OR

(b) A solution containing 0·5 g of KCl dissolves in 100 g of water and freezes at – 0·24o C.
Calculate the degree of dissociation of the salt. (Kf for water = 1.86oC).

Question 10 [3]
An element with density 10 g cm-3 forms a cubic unit cell with edge length of 3 × 10–8 cm. What is the nature of the cubic unit cell if the atomic mass of the element is 81 g mol-1?

Question 11 [3]
Give reasons for the following observations:
(a) Physisorption decreases with an increase in temperature.
(b) Addition of alum purifies water.
(c) Brownian movement stabilizes colloidal solutions.

Question 12
(a) What type of isomers are [Co(NH3)5Br]SO4 and [Co(NH3)5SO4]Br.? Give a chemical test
to distinguish between the two isomers.
(b) Write the structures of optical isomers of the complex ion [Co(en)2Cl2]+ .

Question 13 [3]
(a) Account for the following/Explain why:
(i) Transition metals exhibit variable oxidation states.
(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii.
(iii) Transition metals and their compounds act as a catalyst. [3]

OR

(b) Complete the following chemical equations:
(i) K2Cr2O7 + H2SO4 + FeSO4 →
(ii) K2Cr2O7 + H2SO4 + H2S →
(iii) KMnO4 + H2SO4 + H2C2O4 →

Question 14 [3]
Arrange the following as directed:
(a) Increasing order of basic strength:
Aniline, p – nitroaniline and p – toluidine.
(b) Decreasing order of basic strength in gas phase:
C2H5NH2, (C2H5)2NH, (C2H5)3N and NH3.
(c) Increasing order of solubility in water:
C6H5NH2, (C2H5)2NH, C2H5NH2.

Question 15 [3]
How is silver extracted from its ore? Explain the process with relevant equations.

Question 16 [5]
(a) (i) Resistance of a conductivity cell filled with 0.1 mol L-1 KCl solution is 100 . If the resistance of the same cell when filled with 0·02 mol L-1 KCl solution is 520 ,
calculate the conductivity and molar conductivity of 0·02 mol L-1 KCl solution. The
conductivity of 0·1 mol L-1 KCl solution is 1.29 × 10-2 -1cm-1.
(ii) Define the following terms:
(1) Limiting molar conductivity.
(2) Fuel cell.

OR

(b) (i) Calculate emf of the following cell at 298 K:
Mg(s)  Mg2+ (0·1 M)  Cu2+(0·01M)  Cu(s)
[Given Eo
cell = +2·71 V, 1 Faraday = 96500 C mol-1]
(ii) State Faraday’s first law of electrolysis. Calculate the charge required in terms of
Faraday for the reduction of 1 mole of Cu2+ to Cu.

Question 17 [5]

(a) (i) Account for the following/Explain why:
(1) Interhalogens are more reactive than halogens.
(2) N2 is less reactive at room temperature.
(3) Reducing character increases from NH3 to BiH3.
(ii) Draw structures of the following:
(1) H4P2O7
(2) XeF4

OR

(b) (i) Account for the following/Explain why:
(1) PCl5 exists but NCl5 does not.
(2) Fluorine is a stronger oxidising agent than chlorine.
(3) Bond enthalpy of F2 is less than that of Cl2.
(ii) Complete and balance the following reactions:
(1) FeSO4 + H2SO4 + Cl2 +
(2) P4 + HNO3 + +

Question 18 [5]

(a) (i) Write the product(s) of the following reactions:
(1) CH3COCH3 + H2NOH
(2) 2 C6H5CHO + conc. NaOH
(3) CH3COOH
(ii) Give one chemical test each to distinguish between the following pairs of
compounds:
(i) Benzaldehyde and Benzoic acid
(ii) Propanal and Propanone

OR

(b) (i) Write the chemical equations to illustrate the following name reactions:
(1) Wolff-Kishner reduction.
(2) Aldol condensation.
(3) Cannizzaro reaction.
(ii) Account for the following:
(1) CH3CHO is more reactive with HCN than CH3COCH3.
(2) Carboxylic acids are stronger acids than phenol.
Cl2/P

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