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Chapter 6 Transition Elements Chemistry 12th Class Punjab Short Questions

Question No. 1 - What do you mean by Ligand and Coordination sphere?

Answer No. 1 - Ligand: The atom or ions or neutral molecules,which surrounded the central metal ion and donate electron pair to it called ligands. They must be anions or neutral molecules.
Coordination sphere: The central metal atom or ion along with ligand is called the coordination sphere,It is usually placed in square brackets.It may be anionic cationic or neutral.

Question No. 2 - Give reason that M.P and B.P show maximum value of the middle of 1st transition series.

Answer No. 2 - M.P and B.P show maximum of the middle of 1st transition series and then decrease to a minimum level at the end of the series. This trend in M.P correlates well with the strength of binding force.

Question No. 3 - Define central metal atom or ion?

Answer No. 3 - A metal atom or ion surrounded by a number of ligands is called central metal atom or ion e.g Cu is the central. metal ion.

Question No. 4 - Write name of following complexes: 1.K2 CuCN4

Answer No. 4 - Names of K2 CuCN4 : Potassium Tetracyanocuprate

Question No. 5 - What is the cause of paramagnetic behaviour?

Answer No. 5 - Paramagnetic behaviour is caused by the presence of unpaired electrons in an atom molecule or ion because there is magnetic moment a associated with the spinning electrons. It increase with the increase in the number of unpaired electrons.

Question No. 6 - What is medium carbon steel. Also write its uses.

Answer No. 6 - Medium carbon steel contains 0.2-0.7% Carbon. It is harder than mild steel. It is also malleable and ductile. It is used in making rails, axles, castings.

Question No. 7 - Give reason for the development of colours in the transition complexes?

Answer No. 7 - In transition example, the d-orbits are responsible for the colour development in their compounds. When these orbitals are involved in bonding they split up residing in low energy d orbitals absorb a part of the visible light and jump to the high energy d orbital,This process is called d-d transition.

Question No. 8 - What is Tin Plating?

Answer No. 8 - The process of tin plating consists of dipping the clean sheet of iron in a bath of molten tin and then passing it through hot pair of roller.

Question No. 9 - Why does damaged tin plated iron get rusted quickly?

Answer No. 9 - If the protective coating is damaged, then iron comes into contact with moisture. A galvanic cell is established in which tin acts as cathode and iron as an anode. The electrons flow from iron to tin, where they discharge H+ions, leaving behind OH- in the solution. These hydroxide ions reacts with iron forming which dissolves rapidly in water,From this it can be concluded that plated iron gets rust more rapidly when the protective coating is damaged than the non-plated iron.

Question No. 10 - What are the typical and non typical transition elements?

Answer No. 10 - In order to maintain a rational classification, the elements of group IIB and group IIIB are referred to as non-typical transition elements and the elements in the remaining transition series are called typical transition elements.

Question No. 11 - Write down the chemical formulas of 1. Magnetite 2. Haematite

Answer No. 11 - Formula of Magnetite: Fe3O4
Formula of Haematite : Fe2O3

Question No. 12 - What are Chelates?

Answer No. 12 - When all the donor atoms of a polydentate ligand get coordinated with the same metal ion, a complex is formed which contain one or more rings in its structure and hence is called Chelate,

Question No. 13 - Define Sacrificial corrosion.

Answer No. 13 - If a protective layer of zinc is damaged a galvanic cell is established in the presence of moisture. Iron serves as a cathode and zinc as an anode. Electrons flow from zinc to iron as a result of which Zn decays while Fe remains intact. This is called sacrificial corrosion.

Question No. 14 - What are interstitial compound?

Answer No. 14 - When small non metal atom like H,B,C and N enter the interstices of transition metal and impart useful feature to them, they are called interstitial compound.

Question No. 15 - How the entrapped gases are removed form the steel?

Answer No. 15 - In order to remove entrapped bubbles of gases such, as O2N2 and Co2 a little aluminum or ferro silicon is also added. Aluminium removes nitrogen as nitrate.

Question No. 16 - Why Transition metals show variable valencies?

Answer No. 16 - Transition metals exhibit variable valence or oxidation states. They show variable valencies because of the involvement of the unpaired d electron to s electron in bond information.

Question No. 17 - What are Chelate and what they contain?

Answer No. 17 - Chelate: When all the donor atoms of a polydentate ligand get coordinated with the same metal ion. A complex is formed which contain one or more rings in its structure and hence is called Chelate.

Question No. 18 - Define Ligand.

Answer No. 18 - The atom or ions or neutral molecules,which surrounded the central metal ion and donate electron pair to it called ligands. They must be anions or neutral molecules.

Question No. 19 - Why d- block and f-block elements are called transition elements?

Answer No. 19 - d-block and f-block elements are called transition elements because they are located between the s and p block elements and their properties are in transition between the metallic elements of the s-block and nonmetallic of the p block.

Question No. 20 - Explain chromyl chloride.

Answer No. 20 - When solid potassium dichromate is heated with solid metal chloride in the presence of concentrated sulphuric acid chromyl chloride is produced.

Question No. 21 - What are paramagnetic and Diamagnetic substance?

Answer No. 21 - Substance which are weakly attracted by a strong magnetic field are called paramagnetic substance.
Those substance which are weakly repelled by a strong magnetic field are called diamagnetic substance.

Question No. 22 - Give two use of KMnO4.

Answer No. 22 - 1. It is used as an oxidizing agent.
2. It is used as disinfectant and germicide.
3. It is used in manufacturing of many organic compounds.

Question No. 23 - Name different forms of iron and which is the purest.

Answer No. 23 - Pig Iron or Case Iron : 2.5 to 4.5% Carbon
Wrought iron: 0.12 to 0.25 carbon
Steel : 0.25 - 2.5% Carbon
Purest form of iron is Wrought iron.

Question No. 24 - What is meat by Coordination sphere?

Answer No. 24 - The central metal atom or ion along with ligands is called the coordination sphere. It is usually placed in square brackets. It may be anionic cationic or neutral.

Question No. 25 - Define substitutional alloy? Give an example.

Answer No. 25 - Due to the similarity in the sizes of transition metals, some transition metals atom are able to replace one another in the metallic lattice and from substitutional alloy among themselves. Alloy of steels are an important example of this of material in which iron atoms are substituted by chromium, manganese and nickel atom.

Question No. 26 - How chromate ions are converted into dichromate ions?

Answer No. 26 - Chromate and dichromate ions exist in equilibrium as :
CrO4-2+2H+--------- Cr2O7-2+H2O
On adding the equilibrium will shift towards right and chromate ions will converted into dichromate ions.

Question No. 27 - Define coordination number.

Answer No. 27 - The number of lone pair of electrons provided by the ligand to the central metal atom or ion is called the coordination number of the central metal atom or ion.

Question No. 28 - Define paramagnetic? Which two transition metal ions have strongest paramagnetic behaviour.

Answer No. 28 - The substance which are weakly attracted by a strong magnetic field are called paramagnetic For example Fe2+ and Mn3+.

Question No. 29 - How does process of galvanizing protect iron from rusting?

Answer No. 29 - Galvanizing is done by dipping a sheet of iron in zinc chloride solution and heating. The iron sheet is then removed, rolled into zinc bath and then cooled. In this case it a protective layer of zinc is damages a galvanic cell is established in the presence of moisture. Iron serves as cathode and zinc serve as anode. Electron flow from zinc to iron, as a result of which Zn decays while Fe remains intact. This is called sacrificial corrosion. This is the way galvanizing helps protecting iron from rust.

Question No. 30 - What type of elements form substitution alloy and why?

Answer No. 30 - Owing to the similarity in the size of transition metals, some transition metal atoms are able to replace one another in the metallic lattice and from substitutional alloys among themselves. Alloy steel are important example of this type of material in which iron atoms are substituted by chromium, manganese and nickel atom.

Question No. 31 - Explain d-d transmission?

Answer No. 31 - When d orbitals are involved in bonding, they split up into twin energy levels, one set has a higher energy that the other,The electron residing d orbitals. D orbital a part of the visible light and jump to high energy d orbitals. This process is called d-d transition.

Question No. 32 - Write two uses of K2Cr2O7.

Answer No. 32 - 1. K2Cr2O7 finds extensive use in dyeing.
2. It is used in leather industries for chrome tanning.

Question No. 33 - Define Corrosion?

Answer No. 33 - Any process of chemical decay of metal is due to the action of surrounding medium is called corrosion.

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