Important tips for HSC Chemistry exam preparation

1. 12th
Chemistry
Preparation
Tips
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2. Chemistry Section – I
Unit Unit Max. Marks
No. Marks with
Option
01 Solid State 4 6
02 Solutions and Colligative Properties 5 7
03 Chemical Thermodynamics and Energetics 6 8
04 Electrochemistry 5 7
05 Chemical Kinetics 4 6
06 General Principles and Processes of Isolation of 3 5
Elements
07 P – Block Elements 8 10
Total 35 49
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3. Chemistry Section – II
Unit Unit Max. Marks
No. Marks with
Option
08 d & f – Block Elements 5 6
09 Co-ordination Compounds 3 4
10 Halogen Derivatives of Alkanes ( & Arenes) 4 6
11 Alcohols, Phenols & Ethers 4 6
12 Aldehydes, Ketones & Carboxylic acids 5 7
13 Organic Compounds Containing Nitrogen 4 6
14 Biomolecules 4 6
15 Polymers 3 4
16 Chemistry in Everyday Life 3 4
Total 35 49
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4. Paper Format for Section I & II [ 35 marks each ]
Q – 1 ] Select and write most appropriate answer from the given
alternative for each sub – question. [7]
Q – 2 ] Answer any six [ out of eight ] of the following [ 12 ]
Q – 3 ] Answer any three [ out of four ] of the following [9]
Q – 4 ] Answer any one [ out of two ] of the following [7]
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5. 1 – Mark Questions -
Definition / Statement / Objective Questions
2 – Mark Questions
Big structures of last two topics
Two step conversion, Polymerization processes
Difference - 4 points ( example No Mark ) / Distinguish by reaction
Short Notes, Salient Features of Theory ( 4 points )
Relation between ΔH & ΔU etc
Derivations / Laws of electrolysis
Structures of oxides of Nitrogen /
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6. 2 – Mark Questions
Mfg. Processes ( Haber’s Process for ammonia/ Contact Process)
Allotropes of P or S
Oxy – acids of chlorine
Defects in crystal / limitations / Rault’s law / Diagrams
Resonating structures / Electronic Configurations
2 – point answers / Isomerism, Naming of co – ordination compounds
Numericals
3 – Mark Questions
ABC type crystal structures
Laws and Derivations
Daniel, Cell SHE, Calomel Electrode, Lead Accumulator
3 – point answers / Reaction mechanism / SN1, SN2, Optical activity
Multi step reactions ( balancing not required ) / Methods of preparation
Numericals - Calculations in same units throughout
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7. 12th
Chemistry
8 ] d - f Block
Elements
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8. d – Block Elements :- The atoms of the elements in which the last electron enters the
d – orbital of penultimate ( last but one ) energy level are known as d – block elements.
This indicates that in these elements, last two shells are incompletely filled.

9. Electronic Configuration of first ( 3d ) Transition Series ( 21 Sc – 30 Zn )
[ Ar ] 3d 1 – 10 4 s 1 – 2
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10. Oxidation States of first transition series
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11. Electronic configuration of lanthanides :-
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12. Electronic configuration of lanthanides :-
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13. Lanthanide contraction : - Lanthanide contraction is a term used in chemistry to
describe different but closely related concepts associated with smaller than expected
atomic radii of the elements in the lanthanide series.
Definition :- The decrease in the atomic and ionic radii of the lanthanide elements
with increasing atomic number is known as lanthanide contraction. Thus, the first
element lanthanum has the largest, while the last element lutetium has the smallest
radius among these elements.
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14. 12th
Chemistry
9 ] Co - ordination
Compounds
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15. Isomerism in Coordination Compounds
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16. Stereoisomerism in metal complexes with coordination number 6.
Stereoisomerism in metal complexes with coordination number 6
( octahedral complex ) of the type [ M a4 b2 ] n±

17. Stereoisomerism in metal complexes with coordination number 6.
Stereoisomerism in metal complexes with coordination number 6
( octahedral complex ) of the type [ M a3 b3 ] n±

18. Stereoisomerism in metal complexes with coordination number 6.
Stereoisomerism in metal complexes with coordination number 6
( octahedral complex ) of the type [ M a3 b3 ] n±
For example, consider a complex [ Cr ( NH3 ) 3 Cl 3 ]. The structures of cis and trans
isomers are

19. Structure of complex compounds based on valence bond theory
E ] Structure of Hexaamminecobalt (III) ion, [ CO ( NH3 ) 6 ] 3 +
1.Hexaamminecobalt ( III ) ion, [ CO ( NH3 ) 6 ] 3 + is a cationic complex, oxidation state
of Co is +3 and CN = 6
Electronic configuration : 27Co [ Ar ] 3 d7 4 s2
Electronic configuration : Co 3 + [ Ar ] 3 d6 4s0 4p0
NH3 is a strong ligand, due to spin pairing effect, all the four unpaired electrons in
3d orbital are paired giving two vacant 3d orbitals.

20. Structure of complex compounds based on valence bond theory
E ] Structure of Hexaamminecobalt (III) ion, [ CO ( NH3 ) 6 ] 3 +
The coordination number is 6, Co 3 + ion gets six vacant orbitals by hybridisation of two
3d vacant orbitals, one 4s and three 4p orbitals forming six d2sp3 hybrid orbitals giving
octahedral geometry. It is an inner complex.
6 lone pairs of electrons from 6NH3 ligands are
accommodated in the six vacant d2sp3 hybrid orbitals.
The six hybrid orbitals of Co 3 + overlap with
filled orbitals of NH3 forming 6 coordinate bonds
giving octahedral geometry to the complex.

21. Structure of complex compounds based on valence bond theory
E ] Structure of Hexaamminecobalt (III) ion, [ CO ( NH3 ) 6 ] 3 +
Geometry of complex : Hexaamminecobalt ( III ) ion has a octahedral geometry due
to d2sp3 hybridisation.
Magnetic property : Hexaamminecobalt ( III ) ion has no unpaired electrons. Hence
the complex is diamagnetic. (Magnetic moment, μ = 0 )
Effect of ligands : Ammonia ligands causes 3d electrons to be shifted to 3d – orbitals
so that all the ten electrons are paired up in 3d – orbitals.

22. 12th
Chemistry
10 ] Halogen
Derivatives
11 ] Alcohol Phenol
Ether
12 ] Aldehyde Ketone
Carboxylic Acid
13 ] Compounds
containing Nitrogen
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23. 12th Chemistry
Nomenclature : Common – IUPAC
Methods of preparation / Name Reactions
Chemical Properties / Action of different reagents
Physical Properties
Reaction Mechanism / Effect of Substituent
Resonating Structures
Intext & Exercise Question - MCQ’S
Exceptional Questions
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24. Exceptional Questions
What is hydride shift ? Consider the following reaction : 3 – methylbutan –
2 – ol heated with Hi to form 2 – iodo – 2 – methylbutane ( and not 2 – iodo –
3 – methylbutane ). This can be explained on the basis of hydride shift.
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25. Exceptional Questions
What is hydride shift ?
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26. Exceptional Questions
Secondary carbocation rearranges to a more stable tertiary carbocation by a
hydride ion shift. Nucleophile P ion attacks tertiary carbocation to give
tertiary alkyl iodide.
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27. Exceptional Questions
Phenol is therefore ortho and para directing.
These resonance structures (canonical forms) have negative charge at
ortho and para positions as shown above. Hence phenol gives
electrophilic substitution reactions at ortho or para or at both the
positions but never at meta positions. Phenol is therefore ortho and
para directing.
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28. Exceptional Questions
The ortho and para nitrophenol can be separated by steam distillation.
O – nitrophenol is steam volatile due to intramolecular hydrogen bonding
while p – nitrophenol is less volatile due to intermolecular hydrogen bonding
which causes the association of molecules.
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29. 12th
Chemistry
14 ] Biomolecules
15 ] Polymers
16 ] Chemistry in
Every Day Life
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30. 12th Chemistry
Classification of carbohydrates, Theory, Definitions, Structures
Different classes of drugs, Uses, Side effects
Polymers, Classification, Methods of preparation, Uses
Reaction of glucose, Pyranose, Fructanose Structures.
Intext & Exercise Question - MCQ’S
Exceptional Questions

32. Structure of Cellobiose
The celloboise contains
1 → 4 β glycoside bond.

33. Peptide linkage formation
The structure of proteins show that large number of α - amino acid molecules are
linked to one another through peptide ( – CO – NH – ) linkage.
The peptide linkage is formed by elimination of water molecule from the amino
( – NH2 ) group of one α – ammo acid molecule and the – carboxylic ( – COOH )
group of the next neighbouring α - amino acid molecule.
These carboxylic ( – COOH ) and amino ( – NH2 ) groups undergo condensation
with other α – amino acids. Many peptide linkages thus formed are called polypeptide.
If the molecular weight of such peptides is up to 10,000 then, it is known as
polypeptide and those having molecular weight above 10,000 are known as protein.

34. Vitamins
Some important Vitamins, their Sources and their Deficiency Diseases
No Name of Vitamines Sources Deficiency diseases
.
1. Vitamin A Fish liver oil, carrots, butter Xerophthalmia ( hardening of cornea of eye )
and milk Night blindness
2. Vitamin B1 Yeast, milk, green Beri beri ( loss of appetite, retarded growth )
( Thiamine ) vegetables and cereals
3. Vitamin B2 Milk, eggwhite, liver, Cheilosis ( fissuring at corners of mouth and lips
( Riboflavin ) kidney ), digestive disorders and burning sensation of
the skin.
4. Vitamin B6 Yeast, milk, egg yolk, Convulsions
( Pyridoxine ) cereals and grams
5. Vitamin B12 Meat, fish, egg and curd Pernicious anaemia
( RBC deficient in haemoglobin )
6. Vitamin C Citrus fruits, amla and Scurvy ( bleeding gums )
( Ascorbic acid ) green leafy vegetables
7. Vitamin D Exposure to sunlight, fish Rickets (bone deformities in children )
and egg yolk And osteomalacia
( soft bones and joint pain in adults )
8. Vitamin E Vegetable oils like wheat Increased fragility of RBCs and muscular
germ oil, sunflower oil, etc. weakness
9. Vitamin K Green leafy vegetables Increased blood clotting time

35. Preparation of some important addition polymers
Polyacrylonitrile ( PAN or Orlon ) : -
The addition polymerization of acrylonitrile in
presence of a peroxide catalyst leads to the formation
of polyacrylonitrile.
Polyacrylonitrile is used as a substitute for wool in
making commercial fibres as orlon or acrilan.
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36. Antiseptics : The chemical substances which either kill or prevent the growth of
micro-organisms are called antiseptics. They are safe to be applied on to the living
tissues. e.g. Dettol, iodine, iodoform, boric acid etc.
General uses of antiseptics :
These are not harmful to living tissues and can be safely
applied to wounds, cuts, ulcers and diseased skin surfaces
These are used to reduce odors, resulting from bacterial
decomposition of the body or in mouth.
Therefore they are mixed with face powders, deodorants
and breath purifiers.
These are used in antiseptic cream like soframycin and
furacin.
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37. Examples of Antiseptics
Phenol : They are used for dressing of small wounds. It causes severe burns,
hence other phenolic compounds are used.
Dettol : It is solution of chloro - xylenol is
used in antiseptic cream and for disinfecting
surgical instruments.
Bithional : It is a bacteriostatic agent (inhibits the
growth of micro organisms), used as an agricultural
fungicide. It is used as an anti-infective in deodorants,
shampoos & surgical soaps. lt can cause skin allergy
when exposed sunlight hence not used in cosmetics.
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38. Examples of Antiseptics
Iodine ( I2) : Tincture of iodine is used as a topical antiseptic to kill bacteria. It is
also used in cleaning wounds and sterilizing skin before surgery. It is also used for
disinfection of water, air and sanitization of food utensils.
Iodoform ( CHI3 ): It is used as an external antiseptic for wounds.
Boric acid ( H3BO3 ) : It is a mild antiseptic, used by swimmers as ear drops to
destroy fungal growth. It is also used for eyewash and also as a food preservative
Hydrogen peroxide : It is used as a mild antiseptic, for cleaning ears, sterilizing
surgical or medical instruments. It is also used in treating skin spots, killing the
fungus, dental hygiene and for avoiding contagious diseases. It is used as
germicidal due to release or nascent oxygen.
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39. Cleansing agents : Soaps and detergents.
Mechanism of cleansing action of soaps and detergents : -
Soap and detergents have two parts, a long chain of hydrocarbon tail soluble in oil
and other part (head) soluble in water.
When soap is added to an oily part of cloth or vessel, the hydrocarbon part of soap
dissolves in oil and ionic end of soap dissolves in water.
The soap molecules form micelles where one of the molecules is towards the oil
droplet while ionic end faces out side.
This results in an emulsion in water. The soap micelle assist in dissolving the dirt in
water, thus we can wash our clothes.
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40. Tranquilizers
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