Guess Paper – 2013
Class – XI
Subject -
     MAX MARKS=90


General instructions:

All questions are compulsory.

Marks for each question are indicated against it.

Questions number 1to 8 are very short –answer questions, carrying 1 mark each. Answer these in one word or about one sentence each.

Questions number 9 to18 are short –answer questions, carrying 2 marks each. Answer these in about 30 words each.

Questions number19 to27 are short –answer questions, carrying 3 marks each. Answer these in about 40 words each.

Questions number28 to30 are long-answer questions of 5 marks each. Answer these in about 70 words each.

      7 Use log tables if necessary. Use of calculators is not permitted          



1.Define molality.                                                                                                                               (1)


2.Calculate the number of lines when an electron jumps from 6th level to 2nd level.                            (1)


3. If two discharge tubes A and B are filled with Hydrogen and oxygen respectively, will the electrons and gaseous cations be the same?  Justify your answer.                                                                                          (1)


4. Which of the two is paramagnetic:V+4  or V+5 and why?                                                                 (1)

5 How cathode rays are originated in the discharge tube and how their origin differs from the origin of anode rays?

6 When is a cation highly polarizing? Which alkali metal has the highest polarizing power?               (1)

7.Why is KO2 paramagnetic?                                                                                                               (1)

8 Potassium and Caesium are used in photoelectric cells. Why?                                                                      (1)

9 Concentrated sulphuric acid is 98% H2SO4 by mass and has a density of 1.84g/cm3. What volume of concentrated acid is required to make 5 litres of 0.5 M H2SO4?                                                                                (2)

10 How many atoms and molecules of oxygen are present in 5.6 litres of oxygen at STP?                 (2)

11 Define Empirical formula and molecular formula.                                                                                     (2)


12 Calculate the frequency and wavenumber of a radiation with wavelength 480nm.                                    (2)


13 Write any four properties of d-block elements.                                                                              (2)


14What are isoelectronic species? Arrange the following in increasing ionic radii.                              (2)

                         P3-, S2-, Cl-, K+, Ca 2+


15 What is diagonal relationship? Which elements in the group 1 and 2 show diagonal relationship with which elements? What is the reason?                                                                                                            (2)

16 Write reactions involved in the manufacture of washing soda by Solvay process.                       (2)


17 A large number of fish are suddenly found floating dead on a lake. There is no evidence of toxic dumping but you find an abundance of phytoplankton. Suggest and explain a reason for the fish kill.                                            (2)


18 What do you mean by ozone hole? What are its consequences?                                                                (2)


19 Mothballs contain 93.71% carbon and 6.29% hydrogen. If its molecular mass is 128g/mol, calculate its molecular formula.                                                                                                                                                     (3)


20What do you understand by Heisenberg uncertainty principle?  On the basis of this principle explain why electron cannot exist inside the nucleus? (radius of nucleus=10-15m, mass of electron=9.1X10-31 kg,h=6.626X10-34 Js. (3)



21 Define and name quantum numbers. What information about electron is obtained from each quantum number?                                                                                                                                                      (3)


22 Define Hund’s rule of maximum multiplicity. Write electronic configuration of Chromium (Cr) and Copper(Cu). At No of Cr=24, Cu=29                                                                                                               (3)


23 What is shielding effect? Which properties of elements are affected by shielding effect? Give example.(3)


24 What is atomic radius? What are its types? Which one of them is largest and why?                                (3)


25 Explain why Li and Be show anomalous behavior in their groups?                                                          (3)



26 Explain why?                                                                                                                                             (3)

            (i) Solutions of alkali metals in liquid ammonia are coloured, paramagnetic, conducting and reducing.

(ii) LiCl is covalent whereas NaCl is ionic.

(iii) LiF is insoluble whereas other alkali metal fluorides are soluble.

27 Define water pollution. What is BOD and COD? What is the significance of BOD?                             (3)


28 (a) Define photoelectric effect.                                          (1)

      (b) What is de-broglie equation? What is its significance?  (2)

      (c) What is (n+l) rule?   (1)

      (d) What is spectrum?   (1)



  (a) Define Black Body radiations.                                                                                                                (1)

   (b) Define Aufbau principle.                                                                                                                        (1)

    (c) Write differences between orbit and orbital.                                                                                         (3)



29 What is ionization enthalpy? What are the factors which affect ionization enthalpy? Explain why ionization enthalpy of Al is less than that of Mg and ionization enthalpy of oxygen is less than that of nitrogen which is against the general trend?                                                                                                       (5)


   What is electron gain enthalpy? What are the factors which affect electron gain enthalpy?

Explain why electron gain enthalpy of fluorine is found to be less than the electron gain enthalpy of chlorine ?                                                                                                                                                                            (5)



30  Explain why?

  (i) Beryllium chloride fumes in moist air.

 (ii) Magnesium oxide is used as a refractory material.

(iii) Solubility of hydroxides of alkaline earth metals increases from top to bottom in the group.

(iv) Alkaline earth metals are weaker reducing agents than alkali metals.

(v) LiOH decomposes on heating whereas hydroxides of other alkali metals do not.


 (a) Arrange the following as specified:                                                                                                          (2)

(i) MgO, SrO, K2O and Cs2O(increasing order of basic nature)

(ii) LiCl, LiBr,LiI (decreasing order of covalent character)      

 (b) How would you distinguish between Magnesium and calcium?                                                             (1)

(c) Why Li and Be cannot expand their covalency beyond 4?                                                                       (1)

(d) Why BeCl2 and AlCl3 are used as Lewis acids?                                                                                      (1)





sample paper - 2013

Subject: Chemistry           

Class XI


MM: 70                                                                                     Time:3.00 Hr.


General Instructions :

            1.         All questions are compulsory.

            2.         Questions no. 1 to 8 are very short answer questions and carry 1 mark each.

            3.         Questions no. 9 to 18 are short answer questions and carry 2 marks each.

            4.         Questions no. 19 to 27 are also short answer questions and carry 3 marks each.

            5.         Questions no. 28 to 30 are long answer questions and carry 5 marks each.

            6.         Use log tables if necessary, use of calculators is not allowed.



1.         State the relationship between :                                                                                  1

(i) Empirical and molecular formula.  

(ii) Molecular wt. and vapour density.                                                                                   



2.         Write IUPAC name for;                                                                                             1











3.         Which one of the following atomic orbitals is not possible ? Why ?                          1

            (i) n = 3, l = 1, m = –2             (ii) n = 4, l = 0, m = 0




4.         What is the significance of van der Waal's constant 'b' ?                                           1




5.         What is inductive effect ?.                                                                                          1



6.         State why heat changes in chemical processes are indicated as enthalpy changes and not internal energy changes ?                                                                                                1



7.         What is the condition required for the precipitation to occur ?                                  1



8.         Give an example of a b–elimination reaction.                                                            1



9.         A compound contains 4.07 % hydrogen, 24.27 % carbon and 71.65 % chlorine. It's molar mass is 98.96 g . Deduce  the empirical and molecular formulae.                                    2

            [ At. masses : H = 1 ; O = 16 ; Cl = 35.5 ]



10.       How would you separate a mixture of ethylene, acetylene and ethane ?                   2




11.       Explain the significance of the terms ‘isolated gaseous atom’  and  ‘ground state’ while     defining ionization enthalpy and electron gain enthalpy.                                      2



12.       State why :                                                                                                                  2

            (a) In any period, the alkali metal has lowest ionization energy.

            (b) van der Waals' radii are always larger than covalent radii.


13.       (a) Write an expression to calculate angular momentum of an electron ?

            (b) State the significance of minus sign in Bohr's equation.                                       2




(a) Which quantum number does not follow from the solution of Schrodinger wave                                                             

      equation ?

            (b) An electron has s = + ½ and m = -1, it cannot be present in which of the orbitals and                      why ?



14.       Differentiate between primary and secondary pollutants.                                         2




15.       The following system is in equilibrium ;                                                                     2


                        SO2Cl2 + Heat                  SO2 + Cl2


            What will happen to the temperature of the system if some Clinto it at constant volume ?            Give reason.



16.       Write the conformations of ethane and compare their stability.                                 2




17.       Account for the following :                                                                                        2

            (a) Alkali metals are used in photoelectric cells.

            (b) There is a very large difference between first and second ionization energies of alkali





18.       Explain why :                                                                                                              2


            (i) B––X bond length in BX3 is shorter than theoretically expected values.

            (ii) BCl3</s

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