In the case of `CH_(3)COOH`, which is a weak electrolyte, the number of ions increase on dilution due to an increase in degree of dissociation
`CH_(3)COOH+H_(2)OrarrCH_(3)COO^(-)+H_(3)O^(+)`
In case of storng electrolyte the number of ions re mains the s ame but the interionic attraction decreases.