logical reasoning number series

On increasing the number of resistances connected in series, the total resistance of the series combination "_______"

Write the next number series :

Find the wrong number in the series.

Assign reason for each of the following statement: (i) The largest number of oxidation states are exhibited by the elements in their row transition elements. (ii) The atomic radii decrease in Size with the increasing atomic number in the lanthanoid series

Number of visible lines in Balmer series.