CBSE has released the date sheet of class 12 exams, according to which, exams will begin from February 15. The board has scheduled the chemistry paper on March 12. Here is the sample paper for students:
a) All questions are compulsory.
b) Section A: Q.no. 1 to 5 are very short answer questions and carry 1 mark each.
c) Section B: Q.no. 6 to 12 are short answer questions and carry 2 marks each.
d) Section C: Q.no. 13 to 24 are also short answer questions and carry 3 marks each.
e) Section D: Q.no. 25 to 27 are long answer questions and carry 5 marks each.
f) There is no overall choice. However, an internal choice has been provided in two questions of one
mark, two questions of two marks, four questions of three marks and all the three questions of five
marks weightage. You have to attempt only one of the choices in such questions.
g) Use of log tables if necessary, use of calculators is not allowed.
1) (CH 3 ) 3 C—CHO does not undergo aldol condensation. Comment.
2) Write IUPAC name of the following compound:
3) How is Brownian movement responsible for the stability of sols?
4) In the Arrhenius equation, what does the factor corresponds to?
5) Write the formulas for the following coordination compounds:
Using IUPAC norms write the systematic names of the following: [Co(H2O)6]Cl3
6) Calculate the packing efficiency of a metal crystal for a simple cubic lattice.
7) Determine the values of equilibrium constant (Kc) and ▲G° for the following reaction:
Ni (s) + 2 Ag+ (aq) Ni2+ (aq) + 2 Ag (s) ; E O = 1.05 V (F = 96500 C)
(a) Following reactions occur at cathode during the electrolysis of aqueous copper (II) chloride solution:
8) What happens when:
(i) Orthophosphorus acid is heated?
(ii) XeF 6 undergoes complete hydrolysis?
9) Answer the following questions:
(i) What is meant by chirality of a compound? Give an example.
(ii) Which one of the following compounds is more easily hydrolysed by KOH and why?
10) Explain the following terms with an example for each :
(i) Antifertility drugs
11) (i) What is the scientific explanation for the feeling of depression?
(ii) Name two antidepressant drugs
12) (a) Complete the following chemical reaction equations:
13) (i) If the radius of the octahedral void is ‘r’ and radius of the atoms in close packing is ‘R’. What is the relation between ‘r’ and ‘R’?
(ii) Tungsten crystallizes in body centred cubic unit cell. If the edge of the unit cell is 316.5 pm. What is the radius of tungsten atom?
14) Calculate emf of the following cell at 25 °C:
A strip of nickel metal is placed in a 1 molar solution of Ni(NO 3 ) 2 and a strip of silver metal is placed in a 1-molar solution of AgNO 3 . An electrochemical cell is created when the two solutions are connected by a salt bridge and the two strips are connected by wires to a voltmeter.
(i) Write the balanced equation for the overall reaction occurring in the cell and calculate the cell potential.
(ii) Calculate the cell potential, E, at 25 °C for the cell if the initial concentration of Ni(NO 3 ) 2 is 0.100 molar and the initial concentration of AgNO 3 is 1.00 molar.
15) For the reaction
2NO(g) + Cl 2 (g) → 2NOCl(g), the following data were collected. All the measurements were taken at 263 K:
(a) Write the expression for rate law.
(b) Calculate the value of rate constant and specify its units.
(c) What is the initial rate of disappearance of Cl 2 in experiment no. 4?
The reaction, N 2 (g) + O 2 (g) 2NO(g)
contributes to air pollution whenever a fuel is burnt in air at a high temperature. At 1500
K, equilibrium constant K for it is 1.0 × 10 –5 . Suppose in a case [N 2 ] = 0.80 mol L –1 and
[O 2 ] = 0.20 mol L –1 before any reaction occurs. Calculate the equilibrium concentrations
of the reactants and the product after the mixture has been heated to 1500 K.
16) (a) What are the two types of emulsions and how do they differ from one another? Give one example of each.
(b) Which one of the following electrolytes is most effective for the coagulation of Fe(OH) 3 sol and why?
17. (i) Name the method of refining to obtain low boiling point metals like mercury.
(ii) What is role of pine oil in froth floatation process.
(iii) How is cast iron different from pig iron?
18. Explain the following observations about the transition/inner transition elements:
(i) There is in general an increase in density of element from titanium (Z = 22) to copper (Z = 29).
(ii) There occurs much more frequent metal-metal bonding in compounds of heavy transition elements (3rd series).
(iii) The members in the actinoid series exhibit a large number of oxidation states than the corresponding members in the lanthanoid series.
19. Compare the following complexes with respect to their shape, magnetic behaviour and the hybrid orbitals involved:
(i) Write the IUPAC name of the complex [Cr(NH 3 ) 4 Cl 2 ]Cl.
(ii) What type of isomerism is exhibited by the complex [Co(en) 3 ] 3+ ? (en = ethane-1, 2- diamine)
(iii) Why is [NiCl 4 ] 2– paramagnetic but [Ni(CO) 4 ] is diamagnetic? (At nos.: Cr = 24, Co = 27, Ni = 28)
20) Complete the equations for the following reactions:
21) Write the structure of the monomer of each of the following polymers:
22) Predict the products of the following reaction:
23) Write chemical equations for the following conversions:
(i) Nitrobenzene to benzoic acid.
(ii) Benzyl chloride to 2-phenylethanamine.
(iii) Aniline to benzyl alcohol.
24) (i) Deficiency of which vitamin causes night-blindness?
(ii) Name the base that is found in nucleotide of RNA only.
(iii) Glucose on reaction with HI gives n-hexane. What does it suggest about the structure of glucose?
25) (a) Define the following terms:
(i) Mole fraction (ii) Ideal solution
(b) 15.0 g of an unknown molecular material is dissolved in 450 g of water. The resulting solution freezes at – 0.34°C. What is the molar mass of the material? (Kf for water = 1.86 K kg mol–1)
(a) Explain the following:
(i) Henry’s law about dissolution of a gas in a liquid.
(ii) Boiling point elevation constant for a solvent.
(b) A solution of glycerol (C3H8O3) in water was prepared by dissolving some glycerol in 500 g of water. This solution has a boiling point of 100.42°C. What mass of glycerol was dissolved to make this solution? (Kb for water = 0.512 K kg mol–1)
26) (a) Complete the following chemical equations:
(i) Cu + HNO 3 (dilute) →
(ii) XeF 4 + O2F 2 →
(b) Explain the following observations:
(i) Phosphorus has greater tendency for catenation than nitrogen.
(ii) Oxygen is a gas but sulphur a solid.
(iii) The halogens are coloured. Why?
(a) Complete the following chemical reaction equations:
(i) AgCl (s) + NH 3 (aq) →
(ii) P 4 (s) + NaOH (aq) + H 2 O (l) →
(b) Explain the following observations:
(i) H 2 S is less acidic than H 2 Te.
(ii) Fluorine is a stronger oxidising agent than chlorine.
(iii) Noble gases are the least reactive elements.
27) (a) Write the products of the following reactions:
(b) Give simple chemical tests to distinguish between the following pairs of
(i) Benzaldehyde and Benzoic acid
(ii) Propanal and Propanone
(a) Complete the following reactions:
(b) Give simple chemical tests to distinguish between the following pairs of compounds:
(i) Ethanal and Propanal
(ii) Benzoic acid and phenol
The sample paper is prepared by Mayank Agnihotri, PGT, Chemistry, VidyaGyan School, Sitapur.