Chemistry Sample Papers

CBSE Class 12 Chemistry Sample Paper – p- BLOCK ELEMENTS

MM : 30                            TIME : 40 MIN.
1. PCl5 is ionic in nature in solid state .Explain.
2. Out of NH3 and PH3 which one is more basic and why?
3. Explain why nitric oxide shows different behavior in gaseous and liquid state?
4. Explain why both N and Bi do not form pentahalides while phosphorus does ?
5. What is electron gain enthalpy ? Why its value for S is higher than O?
6. SF4 undergo hydrolysis but not SF6 why?
7. Why Fluorine does not exhibit positive oxidation state?
8. What are interhalogen compounds ? Why they are more reactive than halogens ?
9. Addition of Cl2 to KI solution give it a brown colour but excess of Cl2 turns it colourless. Why?
10.Explain why only Xe can form different types of compounds from all noble gases ?
11.Why CO2 exist as a gas but SiO2 act as solid at room temperature ?
12.Explain why SO2 act as oxidising agent as well as reducing agent but SO3 can act as only oxidising agent ?
13.Write balanced equation for the following
(i) NaCl is heated with sulphuric acid in the presence of MnO2 .
(ii) Cl2 gas is passes into a solution of NaI in water .
14.How are XeO3 and XeO4 prepared ?
15.Complete the following equations :
(i) NaOH (aq) + Cl2 ( aq) →
(ii) P4 + NaOH (aq) + H2O→

 

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CBSE Class 12 Chemistry Test – Solid State

MM : 25 TIME : 40 MIN.
1. Give an example of ionic compound which show Frenkel defect.
2. What type of semiconductor is obtained when silicon is doped with Arsenic?
3. How do metallic and ionic substances differ in conducting electricity ?
4. How are the following properties of the crystals affected by Schottky and Frenkel defects
(i) Density (ii) Electrical Conductivity
5. What is the number of atom in a unit cell of
(i) face centered cubic structure
(ii) body centered cubic structure
6. What are F – centers ? Why are solids containing F – centers paramagnetic?
7. Account for the following :
(i) Fe3O4 is a ferromagnetic at room temperature but becomes paramagnetic at 850 K.
(ii) Zinc oxide on heating becomes yellow.
(iii) Frenkel defect does not change the density of AgCl crystal .
8. Chromium metal crystallizes in a body centered cubic lattice . The length of the unit cell edge is found to be 287 pm . Calculate the atomic radius of chromium
9. The density of Cu metal is 8.95 g cm-3. If the radius of Cu atom is 127.8 pm . Is the copper unit cell a simple cubic , a body centered or a face centered cubic structure ?
10. A cubic solid is made of two elements X and Y . Atoms Y are at corner of the cube and X at body centre . What is the formula of the compound ?
11. Calculate the distance between Na+ and Cl- ion in NaCl crystal if its density is 2.165 g cm-3 (Molar mass on NaCl = 58.5 g mol-1 )

 

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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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CBSE Chemistry Class 11 (Mid Term Exam Model Paper)

CLASS:XI CHEMISTRY

Duration: 3 hrs Maximum marks: 70

General Instructions:

All questions are compulsory.

i)Marks for each question are indicated against it.

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

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

iv)Question numbers 1 9 to 27 are also short answer questions and carry 3 marks each.

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

vi)Use logarithm tables if necessary. Use of calculator is not allowed.

Questions:-

1 Calculate the number of moles in 14g of N2 molecule. (1)
2 What would be the IUPAC and symbol for the elements with atomic numbers 121 and 113. (1)
3 Draw the Lewis dot structure of Nitrite ion (NO2). (1)
4 What do you meant by bond length? (1)
5 Define coefficient of viscosity. What is its S.I. unit? (1)
6 Calculate the oxidation number of phosphorous in H3P2O7and Au in HAuCl4. (1)
7 How the presence of H ions be confirmed in ionic hydrides? (1)
8 What do you understand by the term hydrogen economy ? (1)
9 Chlorine is prepared in the laboratory by treating MnO2 with aqueous HCl according to the reaction:

clip_image001[4]4HCl(aq) + MnO2 (s) 2H2O (l) + MnO2(aq) + Cl2(g)

How many grams of HCl react with 5.0 g of MnO2?

(OR)

clip_image002[6]Calcium carbonate reacts with aqueous HCl to give CaCl2 and CO2 according to the reaction, CaCO3 (s) + 2HCl(aq) CaCl2 (aq) + CO2 (g) +H2O (l).

What mass of CaCO3 is required to react completely with 25ml of 0.75 M HCl?

Atomic mass of Mn=25,Ca=20 Read more…

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