Electronegativity.. Please help me..

Question

If the halogen of element A is mixed with the halide of element B and the color of the kerosene is that of element B. Which is the more electronegative element? why?

Answer 1

element "A" is more electronegative, because it had the strength to take electrons away from element "B", turning its halide "B-" form into the "B2" form

had "B" been more elecronegative , it would have had the strength to maitain the extra electron it had taken when it first became "B-"