The commonly termed ether ,  diethyl ether ( CH₃ CH₂  O CH2 CH₃ )  when  perfectly free from water is called dry ether .

Ether absorbs H₂ O  from atmosphere. Many organic reactions are sensitive to H₂ O , so it must be removed from ether before it being used in the reaction .The best way to remove water from ether is to reflux it over sodium . Sodium will dry out water . However, other a nonreactive water absorber ( or dehydrating agent )  such as MgSO₄ have also been used to remove even traces of water from ether.

,  Faraday's laws of electrolysis is a part of  our syllabus and has been dealt with in the Chapter  " Electrochemistry "as per NCERT class 12 book.    

 Hydrogen and bromine  serves as the system’s electrolyte. During the charge cycle, as power flows into the stack, H₂ is generated and stored in a separate tank. An additional product of the chemical reaction is HBr₃, which is also an electrolyte and is mixed in the same tank as the HBr. During the discharge cycle H₂ is consumed and energy is generated. The H₂ is combined again with the HBr₃ and the system returns to its initial stage with a full tank of HBr. The electrolyte suffers no degradation during the process and the system is self contained with no emissions.

Practice in writing the same reaction more than once and you will find yourself in a much better position. Best of Luck.

The order  of reaction is  =  1

Explanation   :

The order of reaction can be calculated  through following steps -

Step 1 /  Calculate  k  for the reaction using expression  ,

                      k   =   0.693 /  t_1/2

                           = o.693 /  2    ......since  t_1/2 is given as  =  2 hours

                           =  0.3465 hrs^-1

Apply  first order rate expression  ,

      k  =  {tex}\frac{2.303}{t}{/tex} log{tex}\frac{Ro}{R}{/tex}      , at time t =  4 hours ,  

           = {tex}\frac{2.303}{4}log{/tex} {tex}\frac{100}{(100-75)}{/tex}

           = 0.575575 log 4

            =  0.57557 x  0.60206

            =  0.3465 hr^-1 

Thus , same value of rate constant k is  using first order rate equation , confirms the order of reaction = 1         

CFT (Crystal Field Theory ) is a model which describes the breaking of degeneracies in electron orbital states , usually d and f -orbitals , due to static electrical field produced by  ligands surrounding the central metal ion in a coordination compound , thus stabilising the complex. 

Surfactant in  solution are often associated colloids , that is they tend to form aggregates of colloidal dimensions which exist in equilibrium with molecules or ions  from which they are formed . Such aggregated particles  are termed as " micelles ". These are , therefore, also known as associated colloids.

Micelles are formed when a variety of molecules including soaps and detergents are added to water . The molecule may be a fatty acid , a salt of fatty acid ( soaps  ) ,phospholipids  or other similar molecules . the molecule must have strongly polar ' head '   and a non polar chain of hydrocarbons ' tail.When this type of molecule is added to water the nonpolar tails of the  molecule clump in to the centre of a ball like structure     called  micelle , because they are hydrophopic ( or water hating ) The polar head of the molecule presents itself for interaction with water molecules at the ouside of micelles.  

Mischmetal is an alloy of rare earth elements .There is no exact formulation of mischmetal . However , a typical composition of mischmetal  is  ; Cerium  -  50% ,Lanthanum -- 25 % , smaller amounts of praseodymium , neodymeum and a few other trace rare earths  making up the balance .  

{tex}CHF3 \to CF - \; + \;H + {/tex}
{tex}CHCl3 \to CCl3 - \; + H + {/tex}
CF3- is not stable by resonance due to the absence of d-orbitals on F but CCl3- is stable by resonance due to the presence of d-orbitals on Cl. So, CHCl3 is more acidic than CHF3.