CBSE Chemistry Sample Paper for Class XI – 2011

Many times you miss out important things while studying from your notes or text books as for any student it is not possible to study every page or word of book. To ensure that you make enough preparation before examination it is important to solve as much sample papers as you can. This can not only allow you to cover maximum topics of chemistry but it can also improve your writing speed. Following is the example of CBSE chemistry sample paper for class XI for the year 2011:

Time: 1:30 hr, MM : 60

I. Answer the following Questions: (1mark each)

a) Calculate the molecular mass of methane (CH?) and glucose (C?H¹²O?) molecule.

b) Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040(assume the density of water to be one).

c) The mass of an electron is 9.1X10?³¹Kg.If its kinetic energy is 3.0X10?²?J.Calculate its wavelength.

d) Write the general electronic configuration of d-block and f-block elements.

e) Write the atomic number of element present in the third period and seventeenth group of periodic table.

f)Considering the elements F,Cl,O,N, the correct order of their chemical reactivity in terms of oxidizing property is: F>Cl>O>N F>O>Cl>N Cl>F>ON O>F>N>Cl

g) Which out of NH³ and NF³ has higher dipole moment and why?

h) What are intermolecular forces?

i) Write lewis structure of C²H² and N².

j) What are isoelectronic species? Give example.

II.Answer the following questions: (2 marks each)

a) What is the total number of sigma and pi bonds in these molecules: C²H² and C²H4

b) Explain with the help of example polar covalent bond.

c) Would you expect the first ionization enthalpies for two isotopes of the same element to be same or different? Justify your answer.

D) If ten volumes of dihydrogen gas react with five volumes of dioxygen gas, how many volumes of water vapor would be produced?

e) A photon of wavelength 4X10?7 strikes on metal surface , the work function of the metal being 2.13 eV. Calculate i)the energy of the photon (eV), ii) the kinetic energy of the emission, iii)the velocity of the photoelectron (1eV = 1.6020X10?19J).

III. Answer the following questions: (any five – 3 marks each)

a) When electromagnetic radiation of wavelength 300 nm falls on the surface of sodium,electrons are emitted with a kinetic energy of 1.68X10 5 J mol?¹.What is the minimum energy needed to remove maximum wavelength that will cause a photoelectron to be emitted?

b) What is basic difference between the terms electron gain enthalpy, electronegativity and Ionization enthalpy? Give example of each.

c) a)How many sub-shells are associated with n=4? b)How many electrons will be present in the sub-shells having ms value of -½ for n=4.

d) How would you explain the fact that the first ionization enthalpy of sodium is lower than that of magnesium but its second ionization enthalpy is higher than that of magnesium?

e) A vessel of 120 ml capacity contains amount of a gas at 35ºC and 1.2 bar pressure. The gas is transferred to another vessel of volume 180ml at 35ºC. What would be its pressure?

f) Describe the bonding in O² molecule and show the increasing order of energies of various molecular orbitals for O².

IV. Answer the following questions: (any five – 5 marks each)

a)Define Hybridisation with its types giving examples of each.

b)i)State ideal gas equation.

ii) At 25ºC and 760mm oh Hg pressure a gas occupies 600 ml volume. What will be its pressure at a height where temperature is 10ºC and volume of gas is 640ml.

c) Describe the electronic configuration and show the filling of orbitals of the following elements: Cr , Ni, Cu, Si, Se.

d) i) Calcium carbonate reacts with aqueous HCl to give CaCl² and CO² according to the reaction, CaCO³(S)+2 HCl (aq) —à CaCl²b (aq) + CO² (g) + H²O(l) . What mass of CaCO³ is required to react completely wit 25ml of 0.75M HCl? ii)What will be the pressure of the gaseous mixture when 0.5 l of H² at 0.8 bar and 2 l of dioxygen at 0.7 bar are introduced in a 1l vessel at 27ºC?

e) i) Write the Lewis structure of C²H? , N² , HNO? , (CO³ )²? , CH³COOH. ii) Define resonance with the help of example.

f) i) State: Heisenberg Uncertainity Principle, Paulis’s Exclusion Principle, Hund’s rule of maximum Multiplicity ii) A golf ball has a mass og 40 g, and a speed of 45m/sec. If the speed can be measured within accuracy of 2 %, Calculate the uncertainty in the position.

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