» CBSE Chemistry Sample Question Paper - Year 1999 : CBSE Sample Question Papers

Chemistry Class - XII (CBSE)
You are on questions 1 to 20 of Set I

Q.1 Define an atomic orbital. What does angular momentum quantum number tell about an orbital ? (1 mark)

Q.2 Which one of the two, O^-₂ or O ^2-₂ has higher bond order and why?(1 mark)

Q.3 Define dislocation in crystal. (1 mark)

Q.4 Write an example of neutral molecule which is isoelectronic to CIO^-.
(1 mark)

Q.5 Express the relationship between degree of dissociation of an electrolyte and its molar. Conductivity. (1 mark)

Q.6 What for are quaternary ammonium salts widely used? (1 mark)

Q.7 What is meant by Faraday constant? (1 mark)

Q.8 Define the “Ligand". Give an example also. (1 mark)

Q.9 Give an example of the compound in which hydrogen bonding results in the formation of adimer. (1 mark)

Q.10 Write an general formula by which the electronic configurations of the transitions element is represented. (1 mark)

Q.11 Calculate the uncertainty in the position of an electron if the uncertainty in its velocity is 5.7 x 10⁵ ms^-1. (h = 6.6 x 10^-34 Js and mass of electron = 9.1 x 10^-31kg) (1 mark)

Q.12 (i) What is the basic building unit of silicates?
(ii) Draw the structure of asbestos (a silicate containing SiO^2-₃ anions).(2 marks)

Q.13 State Rault’s law. Discuss the factors responsible for the deviation from this low. (2 marks)

Q.14 Calculate the molarity and molality of a 15% solution (by weight) of sulphuric acid of density 1.020 g cm^-3. (Atomic masses : H = 1, O = 16, S = 32 amu) (2 marks)

Q.15 Derive the following equation : (2 marks)
D H = DE + ( Dn) RT

Q.16 A first order reaction is 15% complete in 20 minutes. How long will it take to be 60% complete. (2 marks)

Q.17 Calculate the potential of a zinc-zinc ion electrode in which the zinc ion activity is 0.001 M.
(Eo_Zn²⁺_/Zn. = – 0.76 V, R = 8.314 JK^-1 mol^-1, F = 96,500 mol^-1) (2 marks )

Q.18 Nitric oxide reacts with hydrogen to give nitrogen and water.
2 NO + 2 H₂ –> N₂ + 2 H₂O
The kinetics of this reaction is explained by the following steps :
(i) 2 NO + 2 H₂ –> N₂ + 2 H₂O (slow)
(ii) H_{2O2 + H2 –> 2 H2O (fast)
What is the predicted rate low ? (2 marks)}

Q.19 Write the IUPAC names of the following compounds.
(i)
(ii)

Q.20 Write the reaction involved in the preparation of benzene daizonium chloride. What happens when benzene daizonium chloride reacts with (i) Cu₂Cl₂ and (ii) phenol ?(Given equation for the reaction) (2 marks)

Q.21 Account for the following : (2 marks)
(i) Alkylamines are stronger bases than arylamines.
(ii) Toluene is more easily nitrated than benzene.

Q.22 (i) Why do the transitional metals slow variability in their oxidation state?
(ii) Write formula of a compound where the transitional metal is in +7 oxidation state. (2 marks)

Q.23 Draw the structure and write the hybridisation state of the central atom of each of the following species :
(i) Fe(CO)₅
(ii) trans-[CO(NH₃)₄Cl₂]⁺ (Atomic Number : Fe = 26, CO = 27) (2 marks)

Q.24 What happens during glycolysis and what are the products of glycolysis ? (2 marks)

Q.25 What are antibiotics? Name any two antibiotics which are specific for certain diseases. (2 marks)

Q.26 How are Buna-S and Terylene synthesised? Give chemical equations.(2 marks)

Q.27 When 0.532 g of benzene (C6H6), boiling point of 353 K, is burnt with excess of oxygen in a constant volume system, 22.3 kJ of heat is given out. Calculate H for the combustion process. (R=8.31 J K-1 mol-1) (3 marks)

Q.28 Account for the following :
(i) Of the lanthanide’s, cerium (atomic number 58) forms tetrapositive ion, Ce4+ in aqueous solutions.
(ii) Transition metals have high enthalpy of atomisation.
(iii) Scandium forms no coloured ions and yet it is regarded as a transition element. (3 marks)

Q.29 Explain giving reason for each of the following :
(i) Chloroaceticacid has higher pKa value than acetic acid.
(ii) Carboxylic acid have higher boiling points than the alcohol’s of comparable molecular masses.
(iii) Electrophilic substitution in benzoic acid takes places at meta position.(3 marks)

Q.30 (i) Explain the meaning of the statement, “Absorption is a surface phenomenon.”
(ii) State two features of chemical adsorption which are not found with physical adsorption. (3 marks)

Q.31 (i) What is photosynthesis? Where does it occur in plants?
(ii) Name two products of photosynthesis which are required for the survival of most of the chemotrophs. (3 marks)

Q.32 Complete the following nuclear reactions :
(i) ⁹⁶₄₂Mo(…..,n)⁹⁷₄₃Tc
(ii) ……….( , 2n)²¹¹₈₅At
(iii) ²⁴⁶₉₆ + ¹²₆ –> …… + 4(¹₀n) (3 marks)

Q.33 (a) Account for the following :
(i) Haloalkanes are more reactive than haloarenes.
(ii) Phenols are acidic in nature.
(iii) Unlike phenols, alcohol’s are easily protonated.
(b) Write the reactions involved in the preparation of :
(i) 1, 2-ethanediol from ethene, and
(ii) iodoform from 2-propanol (5 marks)

Q.34 Present a comparative account of the following :
(i) Physical states of nitrogen and phosphorus.
(ii) Maximum covalency numbers of oxygen and sulphur.
(iii) Bond energies of F2 and Cl2.
(iv) Structures of chlorides of boron and aluminium.
(v) Proton affinities of NH3 and PH3 (5 marks)