`{:("1. Electrovalent bonding","a. Benzene"),("2. Covalent bonding","b. Heitler and London"),("3. Valence Bond theory","c. Electron transfer"),("4. Polarised Bond","d. Electron sharing"),("5. Resonance","e. Fajan's theory"),(,"f. Aluminium chloride"):}`

{:(" ""A"," ""B"),("1. Kerosene from water","a. Chemical change"),("2. Iron pins from sand","b. Centrigugation"),("3. Butter from curd","c. Physical change"),("4. Digestion of food separation","d. Magnetic"),("5. Freezing of water","e. Decantation"):}

{:("A","B"),("1) Parenchyma","a) Thin walled packing cells"),("2) Photosynthesis","b) Carbon fixation"),("3) Aerenchyma","c) Localized thickenings"),("4) Collenchyma","d) Buoyancy"),("5) Permanent tissue","e) Sclerenchyma"):}

{:("A","B"),("1) Temperature","a) Kilogram per cubic meter"),("2) Weight","b) Pascal"),("3) Volume", "c) Kelvin"),("4) Density", "d) Newton"),("5) Pressure", "e) Cubic meter"):}

{:(A,B),("1)Smooth endoplasmic reticulum","a)Amoeba"),("2)Lysosome ","b)Nucleus"),("3 Nucleoid ","c)Bacteria"),("4Food Vacuoles","d)Detoxification"),("5)Chromatin material & Nucleolus","e)Suicide bag"):}

{:(1.,"Inert pair effect","a.","Nitric acid"),(2.,"Oxyacid","b.","Cell fuel"),(3.,"Liquid nitrogen","c.","Stabilisation of lower oxidation state"),(4.,"Ostwald process","d.","Ozone"),(5.,"Molecular oxygen","e.","Platinum gauze"),(,,"f.","Refrigerant"):}

Carbon forms covalent bonds by sharing its four valence electrons with four univalent atoms , e.g, hydrogen . After the formation of four bonds, carbon attains the electronic configuration of

Match the following . {:(,"(1)" ,"Valine"," (A) Aromatci essential amino acid"),(,"(2)","Tyrosine"," (B) Fatty acid with 20 carbon atoms"),(,"(3)","Arachidonic acids"," (C) Netural amino acids"),(,"(4)","Lysine"," (D) Fatty acid with 16 carbon atoms"),(,"(5)","Palmitic "," (E) Aromatic amino acid"),(,,"acid"," (F) Basic amino acid"):}

Using valence bond theory account for the geometry and magnetic nature of [NiCl_(4)]^(2-) ion. ("Atomic number of Ni "= 28) .