The d- and f- B...

What are the species A and B in the following.

Maximum magnetic moments of $$ Cr (Z = 24), Mn^{+} (Z=25),$$ and $$Fe^{2+} (Z=26), $$ are x, y, and z. They are in order:

Chloro compound of  vandium has only spin magnetic moment of 1.73 BM. This vanadium chloride has the formula (at.no V = 23)

Calomel $$ (Hg_2Cl_2) $$ on reaction with ammonium hydroxide gives:

The magnetic moment is associated with its spin angular momentum and orbital angular momentum,spin only magnetic value of $$ Cr^{3+} $$ ion is.......

An aqueous solution of $$ FeSO_4.Al_2(SO_4)_3 $$ and chrome alum is heated with excess of $$ Na_2O_2 $$ and filtered. The materials obtained are:

On hearting ammonium dichromate the gas enolved is:

$$ (NH_4)_2 Cr_2 O_7 $$ on heating gives a gas which is also given by:

Comprehension - 2 
 Potassium permanganate is prepared from the mineral pyrolusire $$ MnO_2 $$. Its crystal have deep purple color.It acts as an oxidizing agent in the netural,alkaline as well as acidic medium.In acidic medium,it is used in volumetric analysis for the estimation for ferrous salts,oxalates, etc.The titartion are carried out in the presence of $$ H_2SO_4 $$. However before using it as a titrant,it is first standardized with standard oxalic acid solution or Mohr salt solution.In one of the experiments on 13.4 g of dry pure sodium oxalate (molar mass = $$ 134 g mol^{-1} ) $$
 was disolved in 100 mL of distilled water and then 100 mL of distilled water and then 100 mL of $$ 2.M H_2 SO_4 $$ were added.The solution was cooled to $$ 25.30^oC $$.Now to this solution 0.1 M $$ KMnO_4 $$Solution was added till a very faints pink color persisted.
 (6) The purple color of $$ K_2 MnO_4 $$ is due to :

The radius of $$ La^{3+} $$ (At . No of $$La =57$$ ) is $$ 1.06 \mathring{A} $$ which one of the following given values will be closest to the radius of $$ Lu^{3+}$$ (at no. of $$Lu = 71$$ ) ?