Ans.

Ans. Lanthanide Contraction: The steady decrease in the size of lanthanide ions (M3+) with the increase in atomic no. is called lanthanide contraction.

Causes: As we move down the group from left to right in a lanthanide series, the atomic no. increases and for every proton in the nucleus the extra electron goes to 4f orbital. The 4f orbital is too diffused to shield the nucleus effectively, thus there is a gradual increase in the effective nuclear charge experienced by the outer electrons. Consequently , the attraction of the nucleus for the electrons in the outermost shell increases with the increase of atomic number, thus size decreases.

Consequence of Lanthanide Contraction:

• Separation of Lanthanides: Due to the similar sizes of the lanthanides, it is difficult to separate them but due to lanthanide contraction their properties slightly vary (such as ability to form complexes). The variation in the properties is utilized to separate them.
• Basic Strength of Hydroxide: Due to the lanthanide contraction, size of M3+ions decreases and there is increase in covalent character in M–OH and hence basic character decreases.
• Similarity of second and third transition series:The atomic radii of second row transition elements are almost similar to those of the third row transition elements because the increase in size on moving down the group from second to third transition elements is cancelled by the decrease in size due to the lanthanide contraction.

Ans. Enthalpy of atomisation is the change in enthalpy when one mole of bonds are completely broken to obtain atoms in the gas phase.

Transition elements or D-Block elements have high effective nuclear charge and a large number of valence electrons. Therefore, they form very strong metallic bonds. As a result, the enthalpy of atomization of transition metals is high.

Ans.

1. Ionic radius is the distance between the nucleus and the valence shell of a stable ionic species whereas, atomic radius is the distance between the nucleus and the valence shell of an element in its stable ground state.
2. The ionization energy (IE) is qualitatively defined as the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom to form a cation.

There appears`to be  no straight forward  rule /   answer to this question  as pairing depends upon , 

1. geometry of the complex compound .
2. the central metal atom .
3.  and  also the nature or type of the ligand.

But, in general , it has been observed that  strong field ligands undergo pairing easily as compared to a weak field ligand .

In chemistry , the transition metal has three possible meanings : the IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell , or which can give rise to cations with an incomplete d sub-shell".

Ans. Elements having partially filled d-orbitals in ground state or in excited state, are known as transition elements. They have been placed in the centre of the Periodic Table between s-block and p-block elements.

Ans. Carboxylic acid does not undergo Friedel-Craft's reaction because the Carboxyl group is deactivating and the catalyst AlCl₃(anhy.) gets bonded to Carboxyl group.

Ans. In the transiton metal ions the electrons can be promoted from one energy level to other energy level in the same d-subshell.this phenomenon is called d-d-transition.By this property only transiton elements show colour.

This is because when  metal is a part Of anion we do special ending by using the suffix ate 

But when it is a part of cationic part then we write it's simple name. 

Ans. Once the protective ‘Tin’ layer is broken, the Iron gets exposed to the atmosphere and that portion will corrode faster as the oxidation potential of Fe is higher than that of tin.

Ans. If salt bridge is not used, the current will not flow in the outer circuit after sometime in a galvanic cell.

Ans. A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent.

Ans. Henry's law states that at a constant temperature, the amount of a gas that dissolves in a liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid. It was formulated by William Henry in 1803.

2- iodopropane is easily converted to 2,3 -dimethyl butane through Wurtz reaction . In this reaction the iodopropane is treated with dry sodium in eher  .The  Wurtz reaction for this conversion  is found in sol (ii) as following  -A similar example of Wurtz reaction as in sol (i) is also worth noting .

A will have more vapour pressure since its boiling point is less and hence is more volatile.

Ans. The Wolff Kishner reduction reaction is a method in which a carbonyl compound (aldehyde or a ketone) is reduced to a hydrocarbon.

In this method, the carbonyl compound is heated with a mixture of hydrazine and strong base such as potassium hydroxide or potassium tert-butoxide at a temperature of 453-473 K in ethylene glycol solvent.

During this reduction reaction, the aldehyde or ketone is first treated with hydrazine to form the corresponding hydrazone. On reaction with a strong base, the hydrazone gets converted to a hydrocarbon.

No it's not necessary

Ans. Electron Gain Enthalpy is the energy released when one mole of electron are added to gaseous atoms of an element.

Ionization energy is the minimum amount of energy required to remove an electron from valence shell of a gaseous isolated atom.

The name of the complex  [ Ag(NH₃ )₂ ][ Ag (CN)₂ ]  is

diamminesilver (I) dicynidoargentate (I)

Explanation ,

• It is an ionic complex with ON of silver in cation  ( ie. [Ag(NH)₃ ]₂ ) =  +1
•  The oxidation number of  silver in  complex anion  is  also  +1
• The complex contains the same central atom Ag in cation as well as anion , but the metal is named differently. ( ie.  silver for cation  and  argentum for anion  with a suffix ' -ate ' . Thus, the anion gets the name  " argentate "  

Ans. Aniline does not undergo Friedel craft's reactions because the reagent AlCl3 (the Lewis acid which is used as a catalyst in friedel crafts reaction), being electron deficient acts as a Lewis base. and attacks on the lone pair of nitrogen present in aniline to form an insoluble complex which precipitates out and the reaction does not proceed.

Ans. Quartz can be converted into glass by heating and then cooling it rapidly.

Ans.

• Detergents that can be degraded by bacteria are called biodegradable detergents. Such detergents have straight hydrocarbon chains. For example: Sodium Lauryl Sulphate
• Detergents that cannot be degraded by bacteria are called non-biodegradable detergents. Such detergents have highly-branched hydrocarbon chains. For example: Sodium -4- (1, 3, 5, 7- Tetra Methyl Octyl) Benzene Sulphonate.

Dinesh Kumar, I have already asked Naveen sir about this...No derivations don't come...

Ans. No derivations and structure are not asked in boards. 

Sir Naveen Sharma, kindly clarify the query.....Are the derivations of formulas and structure of drugs asked????

Ma'am cam we know which type of question come in exam

No this type of question are not asked by board papers