CBSE Sample Papers<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nStudents who are going to appear for CBSE Class 12 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme, as prescribed by the CBSE, is given here. Paper 6 of Solved CBSE Sample Paper for Class 12 Chemistry is given below with free PDF download solutions.<\/p>\n
Time Allowed : 3 Hours<\/strong>
\nMax. Marks: 70<\/strong><\/p>\nGeneral Instructions<\/strong><\/p>\n\n- All questions are compulsory.<\/li>\n
- Question number 1<\/strong> to 5<\/strong> are very short answer questions and carry 1<\/strong> mark each.<\/li>\n
- Question number 6<\/strong> to 10<\/strong> are short answer questions and carry 2<\/strong> marks each.<\/li>\n
- Question number 11<\/strong> to 22<\/strong> are also short answer questions and carry 3<\/strong> marks each.<\/li>\n
- Question number 23<\/strong> is a value based question and carry 4<\/strong> marks.<\/li>\n
- Question number 24<\/strong> to 26<\/strong> are long answer questions and carry 5<\/strong> marks each.<\/li>\n
- Use log table, if necessary. Use of calculators is not allowed.<\/li>\n<\/ul>\n
Questions<\/strong><\/p>\nQuestion 1.
\nDraw structure of p-nitroanisole.<\/p>\n
Question 2.
\nWhat causes Brownian movement?<\/p>\n
Question 3.
\nWrite IUPAC name of the following complex
\n[Cr(CN)2<\/sub>(CH3<\/sub>NH2<\/sub>)2<\/sub>(NO)2<\/sub>]Cl<\/p>\nQuestion 4.
\nWrite reaction between phenol and bromine water.<\/p>\n
Question 5.
\nFor the reaction, C2<\/sub>H4<\/sub> + H2<\/sub> \\(\\underrightarrow { Ni } \\) C2<\/sub>H6<\/sub> the rate constant is 3\u00a0\u00d7 10 mol L-1<\/sup> s-1<\/sup>. Predict the order of reaction.<\/p>\nQuestion 6.
\nWhat are colligative properties? Give example of any two colligative properties.<\/p>\n
Question 7.
\nDraw the structure of the following compounds:
\n(i) XeOF4<\/sub>
\n(ii) IBr–<\/sup>2<\/sub><\/p>\nQuestion 8.
\nGive reasons for the following:<\/p>\n
\n- Transition metals show variable oxidation states.<\/li>\n
- Actinoids show variable oxidation states.<\/li>\n<\/ol>\n
Question 9.
\nDefine the following terms:<\/p>\n
\n- Anisotropic solid<\/li>\n
- Ferromagnetic solid<\/li>\n<\/ol>\n
Question 10.
\nWrite definitions of the following:<\/p>\n
\n- Enantiomers<\/li>\n
- Chiral compounds<\/li>\n<\/ol>\n
OR<\/strong>
\nWhat are ambident nucleophiles? Give an example.<\/p>\nQuestion 11.
\nGive one difference in each of the following pairs:<\/p>\n
\n- Hormones and enzymes<\/li>\n
- Nucleotide and nucleoside<\/li>\n
- Starch and glycogen<\/li>\n<\/ol>\n
Question 12.
\nIn the lanthanoid series (Ce \u2192 58 to Lu \u2192 71)<\/p>\n
\n- Which element’s, compound acts as oxidising agent?<\/li>\n
- Which element show +2 oxidation state (name any one)?<\/li>\n
- Which element has largest atomic radii?<\/li>\n<\/ol>\n
Question 13.
\nWrite down the hybridisation and magnetic character of the following complexes according to VBT:<\/p>\n
\n- [CoF6<\/sub>]3-<\/sup><\/li>\n
- [Ni(NH3<\/sub>)4<\/sub>]2+<\/sup><\/li>\n<\/ol>\n
Question 14.
\nComplete the following reactions:
\n
\nOR<\/strong>
\nAccount for the following:<\/p>\n\n- Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.<\/li>\n
- Diazonium salt of aromatic amines are more stable than those of aliphatic amines.<\/li>\n
- Gabriel phthalimide synthesis is preferred for synthesising primary amines.<\/li>\n<\/ol>\n
Question 15.
\nDifferentiate between the following pairs:<\/p>\n
\n- Macromolecular colloids and multimolecular colloids<\/li>\n
- Peptisation and coagulation<\/li>\n
- Electrophoresis and electrodialysis.<\/li>\n<\/ol>\n
Question 16.
\nA decimolar solution of K4<\/sub>[Fe(CN)6<\/sub>] (Potassium ferrocyanide) is 50% dissociated at 300 K. Calculate the osmotic pressure of the solution.<\/p>\nQuestion 17.
\nHow are the following conversions carried out?
\n(i) Propene to propane-1-ol
\n(ii) Benzaldehyde to benzyl alcohol.
\n(iii) Butyl magnesium chloride to pentan-1-ol.<\/p>\n
Question 18.
\nA first order reaction is get 50% completed in 50 minutes, how long will it take [A] to reduced to 60% of its initial concentration?<\/p>\n
Question 19.
\nIf NaCl is doped with 10-3<\/sup> mol % of SrCl2<\/sub>, what is the concentration of cation vacancies?<\/p>\nQuestion 20.
\nDescribe the following:<\/p>\n
\n- Role of stabilizer in the froth floatation process.<\/li>\n
- Role of silica in the metallurgy of copper.<\/li>\n
- Role of cryolite in the metallurgy of aluminium.<\/li>\n<\/ol>\n
Question 21.
\nWrite two uses of each of the following polymers.
\n(i) PVC
\n(ii) Bakelite
\n(iii) Nylon-6, 6<\/p>\n
Question 22.
\nIn the following pairs of halogen compounds which compound undergoes faster SN1 reaction.
\n(i) CH2<\/sub> = CH-CH2<\/sub>Cl and CH3<\/sub>-CH = CH-Cl
\n(ii) CH3<\/sub>CH2<\/sub>-Br and CH3<\/sub>CH2<\/sub>-I
\n<\/p>\nQuestion 23.
\nMr. Naresh an employee in a multinational company due to his hectic schedule and stress started taking sleeping pills. His one of the friend Amit requested him to discontinue taking these pills and asked him to join yoga session and pranayam which improved condition of Mr. Naresh.
\nAfter reading the above passage answer the following questions:<\/p>\n
\n- Write the values shown by Amit.<\/li>\n
- \u2018Nhich class of drugs is used in sleeping pills?<\/li>\n
- Why is it not advisable to take sleeping pills without consultation with the doctor?<\/li>\n
- Give an example of tension relieving drug.<\/li>\n<\/ol>\n
Question 24.
\n(a) Write the product formed in the following:
\n
\n(b) Give simple tests to distinguish the following pairs of compotmds:<\/p>\n
\n- Ethanal and propanal<\/li>\n
- Benzoic acid and ethyl benzoate<\/li>\n
- Benzaldehyde and acetophenone<\/li>\n<\/ol>\n
OR<\/strong>
\n(a) Give reasons:<\/p>\n\n- CH3<\/sub>CHO is more reactive than CH3<\/sub>COCH3<\/sub> towards HCN.<\/li>\n
- 4-Nitrobenzoic acid is more acidic than benzoic acid.<\/li>\n<\/ol>\n
(b) Describe the following:<\/p>\n
\n- Cannizzaro reaction<\/li>\n
- Cross aldol condensation<\/li>\n
- Rosenmund reaction.<\/li>\n<\/ol>\n
Question 25.
\n(a)<\/p>\n
\n- State Kohlrausch law.<\/li>\n
- Find the number of faraday used for electrolysis of one mole A1203.<\/li>\n<\/ol>\n
(b) Find emf of the following electrochemical cell at 298 K.
\nPt | Sn4+<\/sup> (0.02 M), Sn2+<\/sup> (0.04 M) || Fe3+<\/sup> (0.08 M), Fe2+<\/sup> (0.04 M)\u00a0| Pt
\n
\nOR<\/strong>
\n(a) Define the following terms:<\/p>\n\n- Molar conductivity<\/li>\n
- Corrosion<\/li>\n<\/ol>\n
(b) The resistance of a conductivity cell containing 0.001 M KCl solution at 298 K is 1500 \u03a9. What is the cell constant if conductivity of 0.001 M KCl solution at 298 K is 0.146\u00a0\u00d7 10-3<\/sup> S cm-1<\/sup>?<\/p>\nQuestion 26.
\n(a) Complete the following equations:<\/p>\n
\n- I–<\/sup> + O3<\/sub> + H2<\/sub>O \u2192<\/li>\n
- H3<\/sub>PO2<\/sub> + NaOH \u2192<\/li>\n<\/ol>\n
(b)<\/p>\n
\n- Name the noble gas, other than Xe which forms true compound.<\/li>\n
- HCl reacts with powdered iron to give ferrous chloride and not ferric chloride. Assign suitable reason.<\/li>\n
- Which is more reactive SF6<\/sub> or SF4<\/sub>? Give reason for your answer.<\/li>\n<\/ol>\n
OR
\n(a) What happens when<\/p>\n
\n- Cl2<\/sub> reacts with hot concentrated solution of NaOH.<\/li>\n
- XeF6<\/sub> is mixed with SbF5<\/sub> and heated.<\/li>\n<\/ol>\n
(b) Give appropriate reason for each of the following:<\/p>\n
\n- Sulphur shows more catenation property than oxygen.<\/li>\n
- NH3<\/sub> has more boiling point than PH3<\/sub>.<\/li>\n
- Fluorine form only one oxoacid, HOF.<\/li>\n<\/ol>\n
Answers<\/strong><\/p>\nAnswer 1.
\n<\/p>\n
Answer 2.
\nUnbalanced bombardment of particles of dispersion medium on dispersed phase causes brownian movement.<\/p>\n
Answer 3.
\nDicyanidodimethanaminedinitrosylchromium (III) chloride.<\/p>\n
Answer 4.
\n<\/p>\n
Answer 5.
\nZero order reaction.<\/p>\n
Answer 6.
\nColligative property:<\/strong> Those properties of dilute solution of non volatile solute in volatile solvents which depend on the total number of solute particles in per unit volume are called colligative property e.g.<\/p>\n\n- Relative lowering of vapour pressure<\/li>\n
- Elevation in boiling point.<\/li>\n<\/ul>\n
Answer 7.
\n<\/p>\n
Answer 8.<\/p>\n
\n- Since (n-1)d and ns orbitals takes part in bond formation due to their comparable energy, transition elements show variable oxidation states.<\/li>\n
- It is due to comparable energy of 5f, 6d and 7s orbital, any member of electron can participate to bond formation so actionoids show variable oxidation state.<\/li>\n<\/ol>\n
Answer 9.<\/p>\n
\n- Anisotropic solid:<\/strong> Solids which have different arrangement of particles in different directions such as crystalline solids are anisotropic solids. In these solids, physical properties like refractive index are different when measured along different directions in a same solid.<\/li>\n
- Ferromagnetic solid:<\/strong> Solids which are attracted very strongly by a magnetic field are ferromagnetic solids e.g., iron, cobalt, nickel etc. Here, all domains (group of metal ions) orient in same direction of applied magnetic field to produce strong magnetic effect and this persist even when magnetic field is removed.<\/li>\n<\/ol>\n
Answer 10.<\/p>\n
\n- Enantiomers:<\/strong> The optical isomers which are non superimpossible mirror image of one another are known as enantiomers.<\/li>\n
- Chiral compounds:<\/strong> The molecule having atleast a chiral carbon and have non\u00a0superimposable mirror image are known as chiral compounds. A molecule having a single asymmetric carbon atom is chiral is nature.<\/li>\n<\/ol>\n
OR<\/strong>
\nThe nucleophile having two nucleophilic centre but at a time only one attach with electrophilic centre is known as ambident nucleophile, e.g CN–<\/sup> and NC–<\/sup>, NO–<\/sup>2<\/sub> and ONO–<\/sup> etc.<\/p>\nAnswer 11.<\/p>\n
\n- Hormones are biochemical compound responsible for passing information to a body organ to carry out certain work and it itself does not take part in reaction. On the other hand enzymes are protein which acts as biochemical catalyst for specific organic reaction in all living organism.<\/li>\n
- Nucleotide and nucleoside:<\/strong> Nucleoside is a base-sugar unit which contains a sugar (ribose or deoxyribose) and a nitrogenous base. On the other hand, nucleotide is ester of nucleoside and phosphoric acid.
\nIn short, nucleotide gives sugar + base + phosphate on hydrolysis but nucleoside gives only sugar and base.<\/li>\n- Starch and glycogen:<\/strong> Starch is polymer of \u03b1-glucose attached with \u03b1-glycoside linkage and stored in plant body.
\nOn the other hand, glycogen is form of carbohydrate stored in the animal body. Its structure is similar to amylopectin of starch.<\/li>\n<\/ol>\nAnswer 12.<\/p>\n
\n- Cerium (Ce)<\/li>\n
- Europium (Eu)<\/li>\n
- Europium (Eu)<\/li>\n<\/ol>\n
Answer 13.
\n(i)<\/strong> The arrangement of electrons information of [CoF6<\/sub>]3-<\/sup> according to VBT is
\n
\nMagnetic character – Paramagnetic<\/p>\n(ii)<\/strong> The arrangement of electrons in the formation of [Ni(NH3<\/sub>)4<\/sub>]2+<\/sup>, (Ni2+<\/sup> \u2192 3d8<\/sup>)
\n<\/p>\nAnswer 14.
\n
\nOR<\/strong><\/p>\n\n- Methylamine reacts with water to produce OH–<\/sup> ion which combines with FeCl3<\/sub> to give hydrated ferric oxide.\n
\n- CH3<\/sub>NH2<\/sub> + H2<\/sub>O \u2192 CH3<\/sub>NH3<\/sub> + OH–<\/sup><\/li>\n
- FeCl3<\/sub> + OH–<\/sup> \u2192 Fe(OH)3<\/sub> + 3Cl–<\/sup><\/li>\n
- Fe(OH)3<\/sub> \u2192 Fe2<\/sub>O3<\/sub> . xH2<\/sub>O<\/li>\n<\/ol>\n<\/li>\n
- The stability of arenediazonium ion is explained on the basis of resonance.
\n
\nThere is partial double bond character between benzene ring and nitrogen atom so these diazonium salts are stable at lower temperature.<\/li>\n - Gabriel phthalimide synthesis gives pure primary amine and phthalic acid formed regenerated during reaction and it is solid hence can be easily separated.<\/li>\n<\/ol>\n
Answer 15.
\n1.<\/strong> In macromolecular collides particles are of large enough size hence can form colloid easily. These are usually polymers.
\nOn the other hand, in multimolecular colloids the smaller particles aggregated together to come in colloidal range e.g. sulphur sol, gold sol etc.<\/p>\n2.<\/strong> Peptisation:<\/strong> The process in which freshly prepared precipitate into colloidal sol by shaking it with suitable electrolyte in dispersion medium.
\nOn the other hand, in coagulation colloidal system get precipitated out and get settled.<\/p>\n3.<\/strong> In electrophoresis particles of dispersed phase on passing electricity move toward electrode of opposite charge and causes coagulation.
\nWhen the process of dialysis that is, removing dissolved substance from a colloidal solution is carried out under applied electric field, it is known as electrodialysis.<\/p>\nAnswer 16.
\nThe dissociation of K4<\/sub>[FeCN)6<\/sub>] gives following ions
\n
\nConcentration, C = 0.1 m, T = 300 K
\nOsmotic pressure, \u03c0 = i CRT
\n\u03c0 = 3\u00a0\u00d7 0.1\u00a0\u00d7 0.082\u00a0\u00d7 300
\n\u03c0 = 7.38 atm.<\/p>\nAnswer 17.
\nConversion:
\n<\/p>\n
Answer 18.
\nGiven :
\n<\/p>\n
Answer 19.
\nSince for addition of one Sr2+<\/sup> ion two Na+<\/sup> ion need to be displaced i.e. one vacancy will be created for each Sr2+<\/sup> ion.
\nConcentration of cation vacancies = Concentration of Sr2+<\/sup> ion = 6.022\u00a0\u00d7 1023<\/sup>\u00a0\u00d7 \\(\\frac { { 10 }^{ -3 } }{ 100 } \\) ions\/mole of NaCl
\n= 6.022\u00a0\u00d7 1018<\/sup> ions\/mole of NaCl
\nHence concentration of cation vacancies is 6.022\u00a0\u00d7 1018<\/sup>\u00a0vacancies\/mole of NaCl<\/p>\nAnswer 20.<\/p>\n
\n- Froth stabilizers stabilizes the froth i.e. forms thick scum of froth. Some of the stabilizers used are cresol, aniline etc.<\/li>\n
- It acts as flux and removes FeO impurity as slag FeSiO3<\/sub>, which can be easily removed.
\nFeO + SiO2<\/sub> \u2192 FeSiO3<\/sub><\/li>\n- Cryolite reduces melting point of Al2<\/sub>O3<\/sub> and increases electrical conductivity. Molten cryolite acts as solvent for alumina (Al2<\/sub>O3<\/sub>).<\/li>\n<\/ol>\n
Answer 21.<\/p>\n
\n\n\nPolymer<\/strong><\/td>\nUse<\/strong><\/td>\n<\/tr>\n\n(i) PVC<\/td>\n | Waterpipes, rain coat manufacturing, hand bags<\/td>\n<\/tr>\n | \n(ii) Bakelite<\/td>\n | Electrical Switches, computer discs, handles of utensils<\/td>\n<\/tr>\n | \n(iii) Nylon 6, 6<\/td>\n | Textile fibre, parachute making, heavy duty tyres.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Answer 22. \n<\/p>\n Answer 23.<\/p>\n \n- Caring nature, helpful<\/li>\n
- Tranquilizers<\/li>\n
- Most of the drugs taken in higher does may prove fatal and hence a doctor must be consulted before taking drugs.<\/li>\n
- Phenelzine or iproniazid<\/li>\n<\/ol>\n
Answer 24. \n \n(b) 1.<\/strong><\/p>\n | | |