Chemistry Model Papers

CBSE Class 12 Chemistry Sample Paper – HALOALKANES AND HALOARENES

MM : 25                                       TIME : 45 MIN.
1. Give IUPAC names of the following compounds:
(a) CH2=CH-CH – C=CH2
C2H5 Cl
(b) CH3-CH2-CH-C6H5Br
CH3
2. Write the structure of the following organic halogen compounds :
(a) 4-tert-butyl-3-iodoheptane
(b) 2-(2-chlorophenyl)-1-iodooctane
3. Explain the following reaction:
(a) Friedel craft alkylation reaction.
(b) Wurtz reaction
(c) Sandmeyer’s reaction
(d) Finkelstein reaction
4. Convert the following:
(a) Ethane to bromoethene
(b) But-1-ene to but-2-ene
(c) Propene to propyne
(d) Benzyl alcohol to 2-phenylethanoic acid
(e) Aniline to chlorobenzene
5. Explain Markownikoff’s rule with example.
6. Explain the following
(a) Vinyl chloride is hydrolysed more slowly than ethyl chloride
(b) The treatment of alkyl chloride with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH , alkenes are the major products.
7. Distinguish between C2H5Br and C6H5Br through chemical test .
8. What are Enantiomers and Racemic mixtures ?
9. Predict the order of reactivity of the following compounds in SN1 reaction C6H5CH2Br , C6H5CH(C6H5)Br , C6H5CH(CH3)Br , C6H5C(CH3)(C6H5)Br
10. What is chemical name of D.D.T ? How it is prepared ?

 

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CBSE Chemistry Class 12 Sample Paper – ALDEHYDES , KETONES AND CARBOXYLIC ACID

MM : 25                                          TIME : 45 min.
1. Write a chemical equation each to illustrate the following reaction;
(a) Aldol condensation reaction
(b) Cannizzaro reaction
(c) Rosenmund’s reaction
(d) Gattermann – Koch reaction
(e) Clemmensen reduction
2. Convert the following;
(a) Propanone to propene
(b) Propanal to butanone
(c) Benzoic acid to benzaldehyde
(d) Acetone to t-butyl alcohol
(e) Formaldehyde to urotropine
3. Give one chemical test to distinguish Propanal and diethyl ether.
4. Explain why formic acid is more stronger acid than acetic acid ?
5. Explain why carboxylic acid have higher boiling points than alcohols of comparable molecular masses?
6. Why carboxylic acid do not give the characteristic reaction of carbonyl group?
7. Arrange salicylic acid , p-hydroxybenzoic acid , m- hydroxybenzoic acid , benzoic acid in order of increasing acidic strength?
8. Give IUPAC name of Crotonaldehyde .
9. What is Grignard reagent ? How it is used to prepare tertiary butyl alcohol?
10. An alkyl halide when reacts with Aq. NaOH give ‘X’ “X’ in presence of Cu at 573 K gives ‘Y’. ‘Y’ in presence of conc. NaOH gives CH3OH + HCOONa

 

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CBSE Class 12 Chemistry Revision Test – Solutions

MM : 25                                             TIME : 40 MIN.
1. Two liquids A and B boil at 145oC respectively and 190oc respectively . Which of them has a higher vapour pressure at 80oc ?
2. Why is freezing point depression of 0.1 M sodium chloride solution nearly twice that of 0.1M glucose solution ?
3. Define the term molarity of the solution . State one disadvantage in using the molarity as the unit of concentration.
4. Define the term osmotic pressure . What is advantage of using osmotic pressure as compared to other colligative properties for the determination of molar masses of solutes in the solutions ?.
5. Non – ideal solutions exhibit either positive or negative deviation for Raoult’s law . What are these deviations and why are they caused ?
6. What mass of ethylene glycol (molar mass = 62g mol-1) must be added to 5.50 Kg of water to lower the freezing point of water to lower the freezing point of water from 00c to – 10 .0 0c ? [Kf for water = 1.86 K Kg mol-1 )
7. What concentration of nitrogen should be present in a glass of water at room temperature. Assume a temperature of 25oc a total pressure of 1 atmosphere and mole fraction of nitrogen in air of 0.78 (Kh for N2 = 8.42 x 10-7 M/mm Hg) .
8. The boiling point elevation of 0.30 g acetic acid in 100 g benzene is 0.0633 K . Calculate the molar mass of acetic acid from this data . What conclusion can you draw about the molecular state of the solute in the solution ? [Kb = 2.53 K Kg mol-1)
9. An antifreeze solution is prepared from 222.6 g of ethyleneglycol and 200 g of water . Calculate the molality of the solution . If density of this solution be 1.072gml-1 What will be the molarity of the solution?
10. Urea forms an ideal solution in water . Determine the vapour pressure of an aqueous solution containing 10% by mass of urea at 400c ( vapour pressure of water = 55.3 mm of Hg)
11. A 4% solution of sucrose is isotonic with 3% solution of an unknown organic substance . Calculate the molecular mass of unknown substance .

 

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Class XI Chemistry Practice Paper

Central Board of Secondary Education

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CHEMISTRY

CLASS-XI

Time Allowed: 3 hours Maximum Marks: 70

 

General Instructions:

I) All questions are compulsory.

ii) Question number 1 to 8 are short answer questions and carry 1mark each.

iii) Question number 9 to 18 are short answer questions and carry 2 marks each.

iv) Question number 19 to 27 are also short answer questions and carry 3 marks each.

v) Question number 28 to 30 are long answer questions and carry 5 marks each.

vi) Use log tables if necessary

1. Write the electronic configuration of Fe3+ ion (Atomic number of Iron = 26).

2. Why does boron form electron deficient compounds?

3. Tertiary carbocation is more stable than Secondary. Explain why?

4. How does molarity change with temperature?

5. Write the IUPAC name of tertiary butyl alcohol.

6. An atomic orbital has l=2.What are the possible values of m?

7. Find out the oxidation number of manganese in MnO4 and MnO42-.

8. Carbon shows the property of catenation remarkably. Assign a reason for this statement.

9. Write any two points of differences between sigma and pi bond.

OR

a) How many sigma and pi bond are present in the molecule:

CH2=CH-CH=CH2.

b) Which type of hybrid orbital is used by the second carbon atom in the following molecule.

CH≡C-CH2-CH=CH2

10. What is the density of SO2 gas at 27oC. (Atomic Weights: S=32, O=16, R=0.0821l/K/mol.

11. What happens when

a) Lead sulphide is reacted with hydrogen peroxide solution.

b) Chlorine reacts with milk of lime. Write chemical equations for reactions involved.

12. Why do real gases deviate from the ideal behaviour? What are the conditions under which real gases show ideal behaviour?

13. The mass of an electron is 9.1×10-31 Kg. If its kinetic energy is 3×10-25 J, calculate its wavelength.

14. Account for the following

a. The first ionization enthalpy of Mg is greater than that of Al.

b. Oxygen has a lower electron gain enthalpy than sulphur.

15. Calculate the bond order of O2+ and O22- molecular ions and predict their magnetic behaviour.

16. Explain the following:

a. Wurtz reaction

b. Huckles Rule

17. Account for the following :

a. Pentane has higher melting point than 2-methyl butane.

b. Ethyne is more acidic than ethane.

18. What are electrophiles and neucleophiles? Give one example of each.

19. Write the net ionic equation for the reaction of potassium dichromate(VI) with sodium sulphite in an acid solution to give chromium(III) ion and the sulphate ion.

OR

Permanganate (VII) ion in basic solution oxidises iodide ion to produce iodine and manganese dioxide. Write a balanced ionic equation to represent this redox reaction.

20. Write short notes on :

a. Photochemical Smog

b. Ozone Hole

c. Acid Rain

21. a. How will you prepare hydrogen peroxide by industrial method.

b. What happens when

i. ionic hydrides are treated with water?

ii. Boron tri-fluoride reacts with sodium hydride?

22. a. Define the term conjugate acid-base pair.

b. The value of Kc for the reaction 2A↔B+C is 2×10 -3 at 500K at a given time. The composition if reaction mixture is [A]=[B]=[C]= 3×10-4 M. Is the reaction mixture at equilibrium? If not, what is the direction of net reaction?

23. State Le-Chatelier’s Principle. What are its applications in the manufacture of Ammonia in Habers Process?

24. How will you detect the presence of nitrogen in Lassaigne’s Test .

During estimation of nitrogen by kjeldahl’s method the ammonia evolved from 0.5g of the compound neutralised 10ml of 1M H2SO4.Find out the percentage of nitrogen in the compound.

25. Draw the structure of:

a. Di-borane

b.AlCl3

C.BeCl2 in solid state

26. a. What do you understand by common ion effect?

b. Determine the solubility of barium sulphate in 0.05M in barium chloride solution.(Ksp-BaSO4=1.1×10-10).

27. Why lithium shows anomalous behaviour in the group. Give two points of similarities between lithium and magnesium.

28. Explain the following with suitable examples:

a. Inductive Effect.

b. Resonance Effect.

c. Hyper-conjugation.

OR

Define Isomerism. Explain the type of isomerism shown by

a. But-2-ene.

b. Conformations of Ethane.

29. a. SiF6 2- is known where as SiCl6 2- is not. Give possible reason.

b. Why is boric acid considered as a weak acid?

c. What are silicones?

d. CCl4 does not hydrolyse unlike SiCl4.

e. Tl(1) compounds are more stable than Al(1) compounds. Give reasons.

OR

a. Why does BCl3 act as a Lewis acid?

b. What is dry-ice? Why is it so called?

c. What is water gas? How is it prepared?

d. Which is the basic building unit of all silicates?

e. What are zeolites?

30. How will you bring about the following conversions?

i. Propene to 1- bromo-propane.

ii. Benzene to acetophenone.

iii.Ethyne to acetaldenhyde.

iv.Ethene to formaldehyde.

v.Sodium Benzoate to Benzene.

OR

What happens when

a. Ethyne gas is allowed to pass over red hot iron tube.

b. Calcium carbide is treated with water.

c. Propene is treated with dilute KMnO4.

d. Benzene is treated with chlorine in presence of UV light.

e. Phenol is treated with heated zinc dust.

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Class 12 CBSE Chemistry Test Paper

1

Blood cells collapse when suspended in saline water. Account for it.

(1)

2

Name any two neutral oxides.

(1)

3

a) What is the principle behind reverse osmosis?

b) Which substance is usually added into water in the car radiator to act as antifreeze?

(2)

4

State Raoult’s law for a solution containing non-volatile solute.

(2)

     

5

Complete the following equations and also balance them.

i) NH4Cl + Ca(OH)2 clip_image002

ii) Zn + HNO3 clip_image004

iii) P4 + SOCl2clip_image004[1]

iv) MnO4 + HClclip_image006

(2)

6

Draw the structures of the following compounds.

i) Peroxodisulphuric acid

ii) Phosphorous acid and account for the basicity of phosphorous acid.

(2)

7

45 g of ethylene glycol ( C2H6O2) is mixed with 600g of water. Calculate (a) the freezing point depression and (b) the freezing point of the solution.

(3)

8

2 g of benzoic acid (C6H5COOH) dissolved in 25 g of benzene shows a depression in freezing point equal to 1.62 K. Molal depression constant for benzene is 4.9 K Kgmol-1. What is the percentage association of acid if it forms dimer in solution?

(3)

9

Arrange the following in the order indicated.

i) MF, MCl, MBr, MI – Decreasing ionic character.

ii)HOCl, HOBr, HOI – increasing acidic strength

iii)NH3, AsH3, SbH3, PH3 – Decreasing bond dissociation enthalpy

(3)

10

Give reasons for the following observations.

i)Halogens are strong oxidizing agents

ii)Noble gases have large positive electron gain enthalpy.

iii)Sulphur shows paramagnetic character in vapour phase.

(3)

11

How do you prepare XeO3 from XeF4? Write equation. Draw the structure of XeF6. Mention any two applications of He gas.

(3)

12

i) How is O3 estimated quantitatively?

ii)H2SO4 is a moderately strong acid. Give evidence.

ii)Though N2 exhibits +5 oxidation state, it doesnot form pentahalide. Why?

iv)Mention the conditions required for the maximum yield of NH3.

v)What happens when Cl2 reacts with excess NH3 and NH3 reacts with excess Cl2. Give equations.

(5)

13

i) With the help of a graph explain positive deviation.

ii)The vapour pressure of pure liquids A & B are 450 & 700mm Hg respectively at 350K. Find out the composition of the liquid mixture if total vapour pressure is 600mm Hg. Also find the composition of the vapour phase.

(5)

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