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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 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 Test – Organic Compunds containing Nitrogen

MM : 25                                                                                        TIME : 45min.
1. Write a chemical equation each to illustrate the following reaction:
(a) Carbylamine reaction
(b) Hofmann – bromamide reaction
(c) Gabriel phthalimide synthesis
(d) Balz – Schiemann reaction
(e) Diazotisation reaction
2. Separate primary secondary and tertiary amines on the basis of Hinsberg’s method.
3. Convert the following :
(a) Aniline into fluorobenzene
(b) Toluene into p-toluic acid.
(c) Aniline to sulphanilic acid .
4. Why are amines are less acidic than alcohols of comparable molecular masses?
5. How is basic strength of aromatic amines affected by the presence of electron releasing group on the benzene ring?
6. Explain why Amino group in ethylamine is basic but not in acetamide ?
7. Out of aliphatic and aromatic amines which one is soluble in water and why?
8. Give one chemical test to distinguish between benzyl amine and anilne.
9. What happens when ethylamine is treated with CHCl3 in the presence of ethanolic KOH.
10. Discuss the importance of pH in coupling reaction.

 

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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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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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