GUESS PAPER - 2008

Class - XI

SUBJECT – Chemistry

(Set-1)

Time Allotted: 3 hours  Maximum Marks:70

General instructions:

1.     All questions are compulsory.

2.     Section A consists of 10 questions of 1 mark each. Section B consists of 5 questions of 2 marks each. Section C consists of 10 questions of 3 marks each. Section D consists of 4 questions of 5 marks each.

3.     Use of calculators is not permitted. However you can ask for log tables.

Section A

1.     Why does ice melt slowly at higher altitudes?

2.     Name the two elements predicted by Mendeleev’s periodic table.

3.     Draw the structure of benzoic anhydride.

4.     What is the SI unit of molarity?

5.     Give the resonating structures of CO₃^-2 ion.

6.      Predict the reaction of 1N sulphuric acid with Cu. Given: E^oCu⁺², Cu=0.34V

7.     Give reason: The boiling point of alkane decreases with branching.

8.     Why is second electron gain enthalpy taken as positive?

9.     Which physical quantity has the dimensions of Planck’s constant?

10.            Give IUPAC name for CH₃-COCH (C₂H₅)- CH₂- CH₂Cl.

Section B

11.            Give two functions of salt bridge in working of a cell.

12.            Give the value of Kp/Kc for the reaction: CO+ ½ O₂èCO₂ .

13.            Explain with an example, the difference between inductive and elecromeric effect.

14.            How much Fe can be theoretically obtained by the reduction of 1kg of Fe₂SO₄?

15.            What is the name and symbol of the element with atomic number 115? Predict the formula of stable binary compound of the element 115 and sulphur.

Section C

16.            What is hydrogen bonding? What are the requirements for this bonding? A stronger hydrogen bond exists in HF than H₂O yet H₂O boils at higher temperature. Why?

17.            What mass of CaCO₃ is required to react completely with 25 mL of 0.75M HCl according to reaction CaCO₃+2HClè CaCl₂+CO₂+H₂O.

18.            Balance the following reaction in acidic medium:

Cr₂O₇^2-+Fe²⁺+C₂O₄^2-èCr³⁺+Fe³⁺+CO₂         

19.            Discuss the structure of PCl₅ on the basis of hybridization. Why axial bonds are longer as compares to equatorial bonds?

20.            What are f- block elements? Write their general electronic configuration. What are their properties?