NCERT solutions for class 12 chemistry now freely available online
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NCERT Solutions For Class 12 Chemistry Chapter 6 General Principles and Processes of Isolation of Elements
16.1 Why do we need to classify drugs in different ways?
16.2 Explain the term, target molecules or drug targets as used in medicinal chemistry.
16.3 Name the macro molecules that are chosen as drug targets.
16.4 Why should not medicines be taken without consulting doctors?
16.5 Define the term chemotherapy.
16.6 Which forces are involved in holding the drugs to the active site of enzymes?
16.7 While antacids and antiallergic drugs interfere with the function of histamines, why do these not interfere with the function of each other?
16.8 Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem? Name two drugs.
16.9 What is meant by the term broad spectrum antibiotics? Explain.
16.10 How do antiseptics differ from disinfectants? Give one example of each.
16.11 Why are cimetidine and ranitidine better antacids than sodium hydrogencarbonate or magnesium or aluminium hydroxide?
16.12 Name a substance which can be used as an antiseptic as well as disinfectant.
16.13 What are the main constituents of dettol?
16.14 What is tincture of iodine? What is its use?
16.15 What are food preservatives?
16.16 Why is the use of aspartame limited to cold foods and drinks?
16.17 What are artificial sweetening agents? Give two examples.
16.18 Name the sweetening agent used in the preparation of sweets for a diabetic patient.
16.19 What problem arises in using alitame as artificial sweetener?
16.20 How are synthetic detergents better than soaps?
16.21 Explain the following terms with suitable examples:
16.22 What are biodegradable and non-biodegradable detergents? Give one example of each.
16.23 Why do soaps not work in hard water?
16.24 Can you use soaps and synthetic detergents to check the hardness of water?
16.25 Explain the cleansing action of soaps.
16.26 If water contains dissolved calcium hydrogencarbonate, out of soaps and synthetic detergents, which one will you use for cleaning clothes?
16.27 Label the hydrophilic and hydrophobic parts in the following compounds.
15.1 Explain the terms polymer and monomer.
Ans. Polymers are high molecular mass substances consisting of a very large number of simple repeating structural units joined together through covalent bonds in a regular fashion. Polymers are also called macromolecules. Some examples are polythene, nylon-66, bakelite, rubber, etc. Monomers are the. simple and reactive molecules from which the polymers are prepared either by addition or condensation polymerisation. Some examples are ethene, vinyl chloride, acrylonitrile, phenol and formaldehyde etc.
15.2 What are natural and synthetic polymers? Give two examples of each type.
15.3 Distinguish between the terms homopolymer and copolymer and give an example of each.
15.4 How do you explain the functionality of a monomer?
15.5 Define the term polymerisation?
15.6 Is (-NH — CHR—CO-)n a homopolymer or copolymer?
15.7 In which classes, the polymers are classified on the basis of molecular forces?
15.8 How can you differentiate between addition and condensation polymerisatiop?
15.9 Explain the term copolymerisation and give two examples.
15.10 Write the free radical mechanism for the polymerisation of ethene.
15.11 Define thermoplastics and thermo setting polymers with two examples of each
15.12 Write the monomers used for gettingThe following polymers:
15.13 Write the name and structure of one of the common initiators used in free radical addition polymerisation.
15.4 How does the presence of double bonds in rubber molecules influence their structure and reactivity?
15.5 Discuss the main purpose of vulcanisation of rubber.
15.16 What are the monomeric repeating units of Nylon-6 and Nylon 6,6?
15.17 Write the names and structures of the monomers of the following polymers:
15.18 Identify the monomer in the following polymeric structures:
15.19 How is dacron obtained from ethylene glycol and terephthalic acid?
15.20 What is a biodegradable polymer ? Give an example of a biodegradable aliphatic polyester.
14.1 What are monosaccharides ?
14.2 What are reducing sugars?
14.3 Write two main functions of carbohydrates in plants.
14.4 Classify the following into monosaccharides and disaccharides. Ribose, 2-deoxyribose, maltose, galactose, fructose and lactose.
14.5 What do you understand by the term glycosidic linkage?
14.6 What is glycogen? How is it different from starch?
14.7 What are the hydrolysis products of (i) sucrose, and (ii) lactose?
14.8 What is the basic structural difference between starch and cellulose?
14.9 What happens when D-glucose is treated with . the following reagents.
14.10 Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.
14.11 What are essential and non-essential amino acids? Give two examples of each type.
14.12 Define the following as related to proteins:
14.13 What are the common types of secondary structure of proteins?
14.14 What type of bonding helps in stabilising the α-helix structure of proteins?
14.15 Differentiate between globular and fibrous proteins.
14.16 How do you explain the amphoteric behaviour of amino acids?
14.17 What are enzymes?
14.18 What is the effect of denaturation on the structure of proteins?
14.19 How are vitamins classified? Name the vitamin responsible for the coagulation of blood.
14.20 Why are vitamin A and vitamin C essential to us? Give their important sources.
14.21 What are nucleic acids ? Mention their two important functions.
14.22 What is the difference between a nucleoside and a nucleotide?
14.23 The two strands in DNA are not identical but are complementary. Explain.
14.24 Write the important structural and functional differences between DNA and RNA.
14.25 What are the different types of RNA found in the cell?
13.1 Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines.
13.2 Give one chemical test to distinguish between the following pairs of compounds:
13.3 Account for the following
13.4 Arrange the following:
13.5 How wjll you convert:
13.6 Describe a method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved.
13.7 Write short notes on the following:
13.8 Accomplish the following conversions:
13.9 Give the structures of A,B and C in the following reaction:
13.10 An aromatic compound ‘A’on treatment with aqueous ammonia and heating forms compound ‘B’ which on heating with Br2 and KOH forms a compound ‘C’ of molecular formula C6H7N. Write the structures and IUPAC names of compounds A,B and C.
13.11 Complete the following reactions:
13.12 Why cannot aromatic primary amines be prepared by Gabriel phthalimide synthesis?
13.13 Write the reactions of (i) aromatic and (ii) aliphatic primary amines with nitrous acid.
13.14 Give plausible explanation for each of the following:
12.1 What is meant by the following terms? Give an example of the reaction in each case.
12.2 Name the following compounds according to IUPAC system of nomenclature:
12.3 Draw the structures of the following compounds:
12.4 Write the IUPAC names of the following ketones and aldehydes. Wherever possible, give also common names.(i)CH3CO(CH2)4CH3 (ii) CH3CH2CH BrCH2CH(CH3)CHO (iii) CH3(CH2)5CHO (iv) Ph—CH=CH—CHO
12.5 Draw structures of the following derivatives:
12.6 Predict the products formed when cyclohexanecarbaldehyde reacts with following reagents. .
12.7Which of the following compounds would undergo aldol condensation, which the Cannizzaro reaction and which neither? Write the structures of the expected products of aldol condensation and Cannizzaro reaction.
12.8 How will you convert ethanal into the following compounds?
12.9 Write structural formulas and names of four possible aldol condensation products from propanal and butanal. In each case, indicate which aldehyde acts as nucleophile and which as electrophile.
12.10 An organic compound with the molecular formula C9H10O forms 2,4-DNP derivative, reduces Tollen’s reagent and undergoes Cannizzaro reaction. On vigorous oxidation, it gives 1,2-benzenedicarboxylic acid. Identify the compound.
12.11 An organic compound (A) (molecular formula C8H16O2) was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B} and an alcohol (C). Oxidation of (C) with chromic acid produced (B). (Q on dehydration gives but-l-ene. Write equations for the reactions involved.
12.12Arrange the following compounds in increasing order of their property as indicated:
12.13 Give simple chemical tests to distinguish between the following pairs of compounds.
12.14 Row will you prepare the following compounds from benzene? You may use any inorganic reagent and any organic reagent having not more than one carbon atom.
12.15 How will you bring about the following conversions in not more than two steps?
12.16 Describe the following:
12.17 Complete each synthesis by giving missing starting material, reagent or products.
12.18 Give plausible explanation for each of the following:
12.19 An organic compound contains 69-77% carbon, 11-63 % hydrogen and rest oxygen. The molecular mass of the compound is 86. It does not reduce Tottens’ reagent but forms an addition compound with sodium hydrogensulphite and give positive iodoform test. On vigorous oxidation, it gives ethanoic and propanoic acid. Write the possible structure of the compound.
12.20 Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a stronger acid than on phenol. Why?
11.1 Write IUPAC names of the following compounds:
11.2 Write structures of the compounds whose IUPAC names are as follows:
11.3(i) Draw the structures of all isomeric alcohols of molecular formula C5HI20 and give their IUPAC names.
11.4 Explain why propanol has higher boiling point than that of the hydrocarbon, butane?
11.5 Alcohols are comparatively more soluble in water than hydrocarbons of comparable molecular masses. Explain this fact.
11.6 What is meant by hydroboration-oxidation reaction? Illustrate it with an example.
11.7 Give the structures and IUPAC names of monohydric phenols of molecular formula, C7H8O.
11.8 While separating a mixture of ortho and para nitrophenols by steam distillation, name the isomer which will be steam volatile. Give reason.
11.9 Give the equations of reactions for the preparation of phenol from cumene.
11.10 Write chemical reaction for the preparation of phenol from chlorobenzene.
11.11 Write the mechanism of hydration of ethene to yield ethanol.
11.12 You are given benzene, cone. H2S04and NaOH. Write the equations for the preparation of phenol using these reagents.
11.13 Show how will you synthesise
11.14 Give two reactions that show the acidic nature of phenol. Compare its acidity with that of ethanol.
11.15 Explain why is ortho-nitrophenol more acidic than ortho-methoxyphenol?
11.16 Explain how does the – OH group attached to a carbon of benzene ring activate it towards electrophilic substitution?
11.17 Give equations of the following reactions:
11.18 Explain the following with an example
11.19 Write the mechanism of acid dehydration of ethanol to yield ethene.
11.20 How are the following conversions carried out?
11.21 Name the reagents used in the following reactions:
11.22 Give reason for the higher boiling point of ethanol in comparison to methoxymethane.
11.23 Give IUPAC names of the following ethers.
11.24 Write the names of reagents and equations for the preparation of the following ethers by Williamson’s synthesis:
11.25 Illustrate with examples the limitations of Willamson synthesis for the preparation of certain types of ethers.
11.26 How is 1-propoxypropane synthesised from propan-l-ol? Write the mechanism of this reaction.
11.27 Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method.Give reason.
11.28 Write the equation of the reaction of hydrogen iodide with (i)1-propoxypropane (ii)methoxybenzene, and (iii)benzyl ethyl ether
11.29 Explain the fact that in aryl alkyl ethers (i) the alkoxy group activates the benzene ring towards electrophilic substitution and (ii) it directs the incoming substituents to ortho and para positions in benzene ring.
11.30 Write the mechanism of the reaction of HI with methoxymethane.
11.31 Write equations of the following reactions:
11.32 Show how would you synthesise the following alcohols from appropriate alkanes?
11.33 When 3-methylbutant 2-ol is treated with HBr, the following reaction takes place:
10.1 Name the following halides according to IUPAC system and classify them as alkyl, allyl, benzyl (primary, secondary, tertiary), vinyl or aryl halides:
10.2 Give the IUPAC names of the following compounds:
10.3 Write the structures of the following organic halogen compounds:
10.4 Which one of the following has the highest dipole moment?
10.5 A hydrocarbon C5H10 does not react with chlorine in dark but gives a single monochloro compound C5H9CI in bright sunlight. Identify the hydrocarbon.
10.6 Write the isomers of the compound having formula C4H9Br.
10.7 Write the equations for the preparation of 1-iodoobutanefrom (i)1-butanol (ii)1-chlorobutane (iii) but-l-ene.
10.8 What are ambident nucleophiles ? Explain with an example.
10.9 Which compound in each of the following-pairs . will react faster in SN2 reaction with -OH? (i)CH3Br or CH3I
10.10 Predict all the alkenes that would be formed by dehydrohalogenationof the following halides with sodium ethoxide in ethdnol and identify the major alkene:
10.11 How will you bring about the following conversions?
10.12 Explain why
10.13 Give the uses of freon 12, DDT, carbon tetrachloride and iodoform.
10.14 Write the structure of the major organic product in each of the following reactions:
10.15 Write the mechanism of the following reaction:
10.16 Arrange the compounds of each set in order of reactivity towards SN2 displacement:
10.17 Out of C6H5CH2Cl and C6H5CHCIC6H5which is more easily hydrolysed by aqueous KOH.
10.18 p-Dichlorobenzene has higher m.p. and lower solubility than those of o-and m-isomers. Discuss.
10.19 How the following conversions can be carried out:
10.20 The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH, alkenes are major products. Explain.
10.21 Primary alkyl halide C4H9Br (a) reacted with alcoholic KOH to give compound (b) Compound (b) is reacted, with HBr to give (c) which is an isomer of (a). When (a) is reacted with sodium metal it give compound (d), C8H18 which is different from the compound formed when n-butyl bromide is reacted with sodium. Give the structural formula of (a) and write the equations for all the reactions.
10.22 What happens when .
9.1 Explain the bonding in coordination compounds in terms of Werner’s postulates.
9.2 FeS04 solution mixed with (NH4)2SO4solution in 1:1 molar ratio gives the test of,Fe2+ion but CuSO4solution mixed with aqueous ammonia in 1:4 molar ratio does not give the test of Cu2+ ion. Explain why.
9.3 Explain with two examples each of the following: coordination entity, ligand, coordination number, coordination polyhedron, homoleptic and heteroleptic.
9.4 What is meant by unidentate didentate and ambidentate ligands? Give two examples for each.
9.5 Specify the oxidation numbers of the metals in the following coordination entities:
9.6 Using IUPAC norms write the formulas for the following:
9.7 Using IUPAC norms write the systematic names of the following:
9.8 List various types of isomerism possible for coordination compounds, giving an example of each.
9.9 How many geometrical isomers are possible in . the following coordination entities?
9.10 Draw the structures of optical isomers of
9.11 Draw all the isomers (geometrical and optical) of
9.12 Write all the geometrical isomers of [Pt(NH3)(Br)(Cl) (Py)] and how many of these will exhibit optical isomerism?
9.13. Aqueous copper sulphate solution (blue in colour) gives: (i) a green precipitate with aqueous potassium fluoride and (ii)a bright green solution with aqueous potassium chloride. Explain these experimental results.
9.14 What is the coordination entity formed when excess of aqueons KCN is added to an aqueous solution of copper sulphate? Why is it that no precipitate of copper sulphide is obtained when H2S (g) is passed through this solution?
9.15. Discuss the nature of bonding in the following coordination entities on the basis of valence bond theory:
9.16 Draw figure to show the splitting of d-orbitals in an octahedral crystal field.
9.17 What is spectrochemical series? Explain the difference between a weak field ligand and a strong field ligand.
9.18 What is crystal field splitting energy? How does the magnitude of Δ0 decide the actual configuration of d-orbitals in a coordination entity?
9.19 [Cr(NH3)6]3+ is paramagnetic while [Ni(CN)4]2- is diamagnetic. Explain why?
9.20 A solution of [Ni(H20)6]2+ is green but a solution of [Ni(CN)4]2-is colourless. Explain.
9.21 [Fe(CN)6]4- and [Fe(H2O)6]2+ are of different cdlours in dilute solutions. Why?
9.22 Discuss the nature of bonding in metal carbonyls.
9.23 Give the oxidation state, d-orbital occupation and coordination number of the central metal ion in the following complexes:
9.24 Write down the IUPAC name for each of the following complexes and indicate the oxidation state, electronic configuration and coordination number. Also give stereochemistry and magnetic moment of the complex:
9.25 What is meant by stability of a coordination compound in solution? State the factors which govern stability of complexes.
9.26 What is meant by the chelate effect? Give an example.
9.27 Discuss briefly giving an example in each case the role of coordination compounds in:(i)biological systems (iii) analytical chemistry
9.28 How many ions are produced from the complex Co(NH3)6Cl2 in solution?
9.29 Amongst the following ions? Which one has the highest magnetic moment value:
9.30 The oxidation number of cobalt in K[Co(CO)4] is
9.31 Amongst the following, the most stable complex is:
9.32 What will be the correct order for the wavelengths of absorption in the visible region for the following:[Ni(NO2)6]4-, [Ni(NH3)6]2+, [Ni(H20)6]2+?
8.1 Write down the electronic configuration of (i) Cr3+ (ii) Pm3+ (iii) Cu+ (iv) Ce4+(v) Co2+ (vi) Lu2+(vii) Mn2+ (viii) Th4+.
8.2 Why are Mn2+ compounds more stable than Fe2+ towards oxidation to their+3 state?
8.3 Explain briefly how+2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
8.4 To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.
8.5 What may be the stable oxidation state of the transition element with the following delectron configurations in the ground state of their atoms: 3d3,3d5, 3d8 and 3d4?
8.6 Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.
8.7 What is lanthanoid contraction? What are the consequences of lanthanoid contraction?
8.8 What are the characteristics of the transition . elements and why are they called transition elements? Which of the d-block elements may not be regarded as the transition elements?
8.9 In what way is the electronic configuration of the transition elements different from that of the non transition elements?
8.10 What are the different oxidation states exhibited by the lanthanoids?
8.11 Explain giving reasons:
8.12 What are interstitial compounds? Why are such compounds well known for transition metals?
8.13 How is the variability in oxidation states of transition metals different from that of the non transition metals? Illustrate with examples.
8.14 Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?
8.15 Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with:
8.16 Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with (i) iron (II) ions (ii) S02 and (iii) oxalic acid? Write the ionic, equations for the reactions.
8.17 For M2+/M and M3+/M2+ systems the E° values
8.18 Predict which of the following will be coloured in aqueous solution? Ti3+, V3+,Cu+, Sc3+, Mn2+, Fe3+ and Co2+ Give reasons for each.
8.19 Compare the stability of +2 oxidation state for the elements of the first transition series.
8.20 Compare the chemistry of actinoids with that of the lanthanoids with special reference to
8.21 How would you account for the following:
8.22 What is meant by disproportionation? Give two examples of disproportionation reaction in aqueous solution
8.23 Which metal in the first series of transition metals exhibits + 1 oxidation state most frequently and why?
8.24 Calculate the number of unpaired electrons in the following gaseous ions : Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in aqueous solution.
8.25 Give examples and suggest reasons for the following features of the transition metal chemistry:
8.26 Indicate the steps in the preparation of:
8.27 What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.
8.28 What are inner transition elements? Decide which of the following atomic numbers are the atomic numbers of the inner transition elements: 29,59,74,95,102,104.
8.29 The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements.
8.30 Which is the last element in the series of the actinoids? Write the electronic configuration of this element. Comment on the possible oxidation state of this element
8.31 Use Hund’s rule to derive the electronic configuration of Ce3+ ion, and calculate its magnetic moment on the basis of ‘spin-only’ formula.
8.32 Name the members of the lanthanoid series which exhibit+4oxidatk>nstatesandthosewhichexhibit +2 oxidation states. Try to correlate this type of behaviour with the electronic configurations of these elements.
8.33 Compare the chemistry of actinoids with that of lanthanoids with reference to:
8.34 Write the electronic configurations of the elements with the atomic numbers 61,91,101 and 109.
8.35 Com pare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points:
8.36 Write down the number of 3d electrons in each of the following ions:Ti2+, V2+, Cr3+, Mn2+, Fe2+, Fe2+, Co2+, Ni2+ and Cu2+. Indicate how would you expect the five 3d orbitals to be occupied for these hydrated ions (octahedral).
8.37 Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.
8.38 What can be inferred from the magnetic moment values of the following complex species?