Solutions of two electrolytes ‘A’ and ‘B’are diluted. The 
of ‘B’ increases 1.5 times while that of A increases 25 times. Which of the two is a strong electrolyte? Justify your answer.
Molar conductivity of a solution at a given concentration is the conductance of volume V of a solution containing one mole of electrolyte kept between two electrodes with an area of cross section A and distance of unit length.
Molar conductivity, Λm= 
or Λm= κV
where
κ is the conductivity
A is the area of cross-section and
l is the distance between the electrodes.
For weak electrolytes the number of ions increases and the degree of dissociation increases with dilution and the increase is drastic. Hence, A has to be a weak electrolyte whereas B has to be a strong electrolyte because for strong electrolytes the number of ions does not change, but interionic distance decreases and therefore the increase is gradual.
Thus, electrolyte B is strong as on dilution the number of ions remains the same, only interionic attraction decreases; therefore, the increase in Λm is small.