CLASS XI

CHEMISTRY

SAMPLE PAPER-3

 

Max. Marks – 70                                                                                                                 Time allowed: 3 hours

General Instructions:

(i) All the questions are compulsory.

(ii) Questions 1 to 4, carry one mark each and questions 5 and 6, carry 2 marks.

(iii) Questions 7 to 10 are short answer questions carrying one mark each.

(iv) Questions 11 to 15 are also short answer questions carrying two marks each.

(v) Questions 16 to 24 are also short answer questions carrying three marks each.

(vi) Questions 25 to 27 are assertion- reason questions carry two marks each.

(vii) Questions 28 to 30 are long answer questions and carry five marks each.

(viii) Use log tables for calculations if necessary.

 

Question 1:

Na, Ca & Ba impart colours ______, ______, & _______ respectively to the flame.

1) Yellow, Apple green, Brick red

2) Brick red, Yellow, Apple green

3) Yellow, Brick red, Apple green

4) Apple green, Brick red, Yellow

 

Question 2:

The molar mass in grams is numerically equal to __________ in u.

1) Atomic mass

2) Formula mass

3) Molecular mass

4) All of the above                                                                                            

 

Question 3:

The number of sigma & pi bonds in 1-butene-3-yne are

a) 5 sigma; 5 pi

b) 7 sigma; 3 pi

c) 8 sigma; 2 pi

d) 6 sigma; 4 pi

 

Question 4:

pH of the solution of salt of weak acid & strong base is given by

1) pH = 7 + ½ (pK_a - pK_b)

2) pH = 7 + ½ (pK_a + logC)

3) pH = 7 - ½ (pK_b + logC)

4) None of the above                                                                                

 

Question 5:

Which of the following sets of quantum numbers are correct?

        n        l       m_l

(i)    1        1      +2

(ii)   3        2      +2

(iii)  4        3      –3

(iv)  3        4      –2

 

Question 6:

Electrophiles are electron seeking species. Which of the following sets consist of electrophiles only.

(i) BF₃, NH₃, H₂O

(ii) AlCl₃, SO₃, ⁺NO₂

(iii) ⁺NO₂, ⁺CH₃, CH₃ – ⁺C = O

(iv) ^-C₂H₅, ^.C₂H₅, ⁺C₂H₅                                                                                      

 

Question 7:

Which element do you think would have been named by

(i) Lawrence Berkeley laboratory

(ii) Seaborg’s group                                                                                   

 

Question 8:

Write the reaction of preparation of BeCl₂ from BeO.

 

Question 9:

Write the reaction of cyclic polymerisation of Ethyne to benzene.

 

Question 10:

Why does rain water have a pH of about 5 – 6?

 

Question 11:

a) Number of π bonds and σ bonds in the following structure is

b) Melting point of compound showing intermolecular H-bonding is more or less than melting point of compound showing intramolecular H-bonding?

 

Question 12:

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

Question 13:

Classify the following species into Lewis acids & Lewis bases and show how these act as such:

(a) HO^-

(b) F^-

(c) H⁺

(d) BCl₃                                                                                                                

 

Question 14:

Using stock notation represent the following compounds:

1) V₂O₅

2) Cu₂O.

 

Question 15:

Give 2 reactions showing that heavy water is used for the preparation of other deuterium compounds.

 

Question 16:

a) Wooden ball of 200 g does not move like a wave when it is thrown at a speed of 200 km/h. Calculate the wavelength of the wooden ball and explain why it does not show wave nature.

b) Calculate the wavelength of radiation in nanometer having frequency 5.89 × 10¹⁴ Hz. Which part of the electromagnetic spectrum does it belong to?

 

Question 17:

a) How Henry Moseley showed that the atomic number is more fundamental property of an element than its atomic mass?

b) Find out group, period & block of element having Z = 82.

 

Question 18:

Define

a) Bond Length

b) Bond angle

c) Bond Enthalpy

 

Question 19:

At what temperature will the root mean square velocity of SO₂ be same as that of methane at 300 K?                                                                                                                 

 

Question 20:

The ionization constant of HF, HCOOH and HCN at 298K are 6.8 x 10^-4, 1.8 x 10^-4 and 4.8 x 10^-9 respectively. Calculate the ionization constants of the corresponding conjugate base.  

 

Question 21:

Write balanced chemical equation for the following reaction: Reaction of liquid hydrazine (N₂H₄) with chlorate ion (ClO₃^–) in basic medium produces nitric oxide gas and chloride ion in gaseous state. (Balance by ion electron method)

 

Question 22:

a) Give one reaction each showing oxidising and reducing action of H₂O₂ in acidic & basic mediums.

b) How is methanol prepared from Dihydrogen? Give chemical reaction.

 

Question 23:

a) Why gypsum is added during of setting of cement?

b) What is cement clinker?

c) How is Plaster of Paris prepared?

 

Question 24:

i) How alkene can be obtained from vicinal dihalides?                         

ii) Prepare Deuteropropane from isopropyl bromide                           

iii) How is ethyne prepared on industrial scale from Calcium carbide?                    

 

Question 25:

Assertion (A): Ozone is destroyed by solar radiations in upper stratosphere.

Reason (R): Thinning of ozone layer allows excessive UV radiations to reach the surface of earth.

(i) A and R both are correct but R is not the explanation of A.

(ii) A is false but R is correct.

(iii) A and R both are correct and R is the correct explanation of A.

(iv) A and R both are incorrect.                                                                                            

 

Question 26:

Assertion (A): The first ionization enthalpy of alkali metals decreases down the group. Reason (R): Increase in number of orbitals increases the shielding effect which outweighs the increasing nuclear charge, therefore, the removal of outermost electron requires less energy on moving down the group.

(i) A and R both are correct but R is not the explanation of A.

(ii) A is false but R is correct.

(iii) A and R both are correct and R is the correct explanation of A.

(iv) A and R both are incorrect.                                                                                            

 

Question 27:

Assertion (A): Nitration of benzene requires the use of concentrated sulphuric acid and nitric acid.

Reason (R): The mixture of acids produces the electrophile for the reaction.

(i) A and R both are correct but R is not the explanation of A.

(ii) A is false but R is correct.

(iii) A and R both are correct and R is the correct explanation of A.

(iv) A and R both are incorrect.                                                                                

 

Question 28:

(i) Define the following:

(a) Lattice enthalpy

(b) First law of thermodynamics                                                                  

(ii) Find out whether it is possible to reduce MgO using carbon at 298K. If not, at what temperature it becomes spontaneous. For reaction

MgO(s) + C(s)                 Mg(s) + CO(g)

Δ_rH⁰ = 491.18 kJ/mol, Δ_rS⁰ = 197.67 J/K mol                                                        

 

Question 29:

a) SiCl₆^2- does not exist but SiF₆^2- exists. Explain.

b) What happens when Boron trichloride reacts with Hydrogen at high temperature?

c) Why Anhydrous AlCl₃ is more soluble in diethyl ether?

d) Although Al is above Hydrogen in the electrochemical series, it is stable in air and water. Why?

 

Question 30:

Draw the structures of following compounds whose IUPAC names are given below:

1) 3-Ethyl-5-methylheptane

2) 3-Ethyl-1,1-dimethylcyclohexane

3) Cyclohexene

4) Hexane-2,4-dione

5) 5-Oxohexanoic acid

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