CBSE practice Questions

CBSE Sample Paper Chemistry Class 12 [PDF]

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This CBSE Sample Paper Chemistry Class 12 includes 30 questions based on latest 12 CBSE Board Chemistry exam pattern.

1 MARK QUESTIONS

Question: Name the two components of starch.

Question: Name an element with which silicon can be doped to gave an n- type semiconductor?

Question: What is meant by term Broadspectrum antibiotic, Give example?

Question: What is the co-ordination number of hcp crystals ?

Question: What is the function of cryolite in the extraction of Aluminium?

Question: How many effective sodium ions are located at the centres of the faces of a unit cell in sodium chloride crystal?

Question: Arrange the following monoxides of transition metals on the basis of decreasing basic character TiO, VO, CrO, FeO.

Question: Why Amine are more basic than comparable alcohols?

Question: Draw the structure of Pent-2-enal.

Question: What is Hardy-Schulze rule?

Question: When proteins said to be denatured?

Question: What do you observe when Red Blood corpuscles are placed in  (i) 1% NaCl Solution, (ii) 0.5% NaCl Solution?

Question: A plot of rate of reaction (y-axis) versus concentration of reaction (x-axis) gives a line parallel to x-axis. What is the order of the reaction?

Question: Write the formula for tetraamineaquachloridocobalt(III)chloride.

Question: Write the structures of the monomer of the following polymer (1)Dactron (2)Buna-N

Question: Name a narcotic analgesic.

Question: Name the reagent which is used to convert phenol into picric acid.

Question: An element has a body centred cubic structure with a cell edge of 288 pm. The density of the element is 7.2 g/cc. How many atoms are present in 208 g of the element?

2 MARK QUESTIONS

Question: Atoms of element B form hcp lattice and those of element A occupy 2/3rd of tetrahedral voids. What is the formula of the compound formed by the elements A and B?

Question: The conductivity of 0.20 M solution of KCl at 298K is 0.0248 S/cm.Calculate its molar conductivity.

Question: Distinguish between dettol and a 1% solution of phenol. Also name the antiseptic added in soaps.

Question: Why do the transition elements exhibit higher enthalpies of atomization?

Question: Draw the structure ofchromate and dichromate ions?

Question: Name the monomer from which Nylon – 6 is manufactured.

Question: (a) Distinguish between order and molecularity of a reaction.
(b) What is meant by pseudo first order reaction? Give an example of it.

Question: A mixed oxide of iron and chromium is fused with sodiumcarbonate in the presence of air to form a compound A, which on treatment with sulphuric acid gives an orange compound B. Write equations to show the conversions.

Question: A primary alkyl halide C4H9Br reacted with alcoholic KOH to give a compound A, this compound reacted with HBr to give B which is an isomer of the parent compound. Write the reaction for the conversion of A to B and the structures of the isomers.

Question: Explain the difference between Buna – N and Buna – S.

Question: Atoms of element B form hcp lattice and those of element A occupy 2/3rd of tetrahedral voids. What is the formula of the compound formed by the elements A and B?

Question: Draw figure to show the splitting of d-orbitals in an octahedral crystal field.

Question: Distinguish between:
(i) Hexagonal Close packing and cubic close packing.
(ii) Tetrahedral void and Octahedral void.

Question: A certain reaction is 50% complete in 20 minutes at 300 K and the same reaction is again 50% complete in 5 minutes at 350 K. Calculate the activation energy if it is a first order reaction.

Question: Write short note on any two polyhalogen compounds.

Question: A mixed oxide of iron and chromium is fused with sodiumcarbonate in the presence of air to form a compound A, which on treatment with sulphuric acid gives an orange compound B. Write equations to show the conversions.

Question: Define thermoplastics and thermosetting polymers with two examples of each.

Question: Explain why:
(1) The dipole moment of chloroform is lower than that of cyclohexyl chloride?
(2) Grignard reagents should be prepared under anhydrous conditions?

3 MARK QUESTIONS

Question: Write the cell notation for a cell having magnesium anode and copper cathode. Also calculate the emf of this cell where concentration of magnesium ions is 0.001 M and copper ions is 0.0001 M. The standard emf of Mg is -2.36 V and Cu is 0.34 V.

Question: (a) Give the mechanism in forming rusting of iron.
(b) Why molar conductivity of weak electrolyte at infinite dilution cannot be determined directly.
(c) What are the advantages of using fuel cell?

Question: Why do KCl and acetic acid show abnormal molar mass? What do we infer when Vant Hoff’s factor is unity.

Question: What is Kraft temperature? Distinguish between lyophilic and lyophobic colloides with an example each.

Question: Explain the following: (a) Transition metals exhibit variable oxidation of states. (b) Chromium metal has high melting point. (c) Transition metals form coloured ions.

Question: What are food preservatives? Give one examples.

Question: What happens when D-glucose is treated with: (a) HI, (b) Bromine water (c) Nitric acid.

Question: Write short note and reaction : Cannizaro reaction , Decarboxylation reaction.

Question: Distinguish between: (a) Phenol and ethanol, (b) Propanol and 2-propanol (c) Why are phenols more acidic than alcohols?

Question: Explain: (a) There is a greater range of oxidation states among the actinoids than lanthanoids. (b) Atomic radii of second and third d- series elements almost same. (c) The highest oxidation state of a metal exhibited in its oxides or fluorides only.

Question: Define the following with relation to proteins: (a) Peptide linkage, (b) Primary structure (c) Denaturation.

Question: (a) Write short note on Gabriel phtalimide synthesis. (b) Convert aniline to phenol. (c) Draw the structure of the zwitter ion of sulphanilic acid.

5 MARK QUESTIONS

Question: (a) Show that for a zero order reaction, half life is directly proportional to the initial concentration of the reactant, but in a first order reaction, the half life of the reaction is independent of the initial concentration of reactant. (b) A first order reaction has a rate constant of 0.00115/s.How long will 5 g of this reactant take to reduce to 3 g?

Question: (a) Convert carbondioxide to acetic acid. (b) Convert butanal to butanoic acid. (c) Convert ethylbenzene to benzoic acid. (d) Draw the structure of 4-Chloropentan-2-one. (e) Give the product obtained when benzoic acid is treated with conc.sulphuric acid and conc.nitric acid (Nitrating Mixture).

Question: Give the answer of following:  (1) What is meant by disproportionation  of an oxidation state . Give example. (2) K2PtCl6 is well known compound whereas coorsponding Ni compound is not known why? (3) indicate the steps the preparation of K2Cr2O7  from chromite ore? (4) Explain why transistion element show variable oxidation state and write possible oxidation state  shown by Mn?

Question: (a) Aldehydes are generally more reactive than ketones in nucleophilic addition reactions. Why? (b) What is Aldol condensation? Explain with example. (c) Explain Cannizzaro’s reaction.

Question: (a) Convert carbondioxide to acetic acid. (b) Convert butanal to butanoic acid. (c) Convert ethylbenzene to benzoic acid. (d) Draw the structure of 4-Chloropentan-2-one. (e) Give the product obtained when benzoic acid is treated with conc.sulphuric acid and conc.nitric acid(Nitrating Mixture).

Question: (a) State Raoult’s law for solutions containing a non volatile solute. (b) Sodium chloride or calcium chloride is used to clear snow from the roads. Why? (c) 0.5 g of KCl was dissolved in 100 g water and the solution originally at 200C, froze at –0.240C. Calculate the percentage ionization of salt. Kf per 1000 g of water = 1.86 K.

Question: (i) Explain a) abnormal molar mass, (b) azeotropic mixture. (c) negative deviation from Rault,s law. (ii) What are the factors responsible for the solubility of gases in liquid?

Question: (a) Ammonia forms hydrogen bonds but not phosphene. Why? (b) What led Bartlet to carry out reaction between xenon and platinumhexafluoride?
(c) Why are halogens coloured? d) Draw the structure of xenondifluoride and give the equation for its preparation.

Question: (a) What is the basicity of orthophosphoric acid? (b) The covalency of oxygen is limited to four. Why? (c) Draw the structure of pyrosulphuric acid. (d) Noble gases have very low boiling points. Why? (e) Write a balanced equation for the reaction between xenonhexafluoride and water.

Question: (a) Aldehydes are generally more reactive than ketones in nucleophilic addition reactions. Why? (b) What is Aldol condensation? Explain with example. (c) Explain Cannizzaro’s reaction.

Question: (a) Ammonia forms hydrogen bonds but not phosphene. Why? (b) What led Bartlet to carry out reaction between xenon and platinumhexafluoride? (c) Why are halogens coloured? (d) Draw the structure of xenondifluoride and give the equation for its preparation.

Question: (a) The rate constants of a reaction at 500 K and 700 K are 0.02/s and 0.07/s respectively. Calculate activation energy. (R=8.314 J/K/mol) (b) A reaction is first order in A and second order in B.Write the rate law expression and how will the rate be affected if concentration of B is increased three times?

Download all 30 questions using link below

Paper 1: https://examsegg.com/downloads/12/cbse-sample-paper-chemistry-class-12.pdf

Paper 2: https://examsegg.com/downloads/12/cbse-sample-paper-chemistry-2014.pdf

Paper 3: https://examsegg.com/downloads/12/cbse-class-12-sample-paper-chemistry.pdf

Paper 4: https://examsegg.com/downloads/12/cbse-12-sample-paper-chemistry.pdf

Paper 5: https://examsegg.com/downloads/12/cbse-chemistry-class-12-practice-paper.pdf

Paper 6: https://examsegg.com/downloads/12/cbse-12-sample-paper-of-chemistry.pdf

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