The molar mass of X would be 63.55 g/mol and the chemical symbol of X would be Cu (copper).
From the equation of the reaction: F2+2XBr⟶Br2+2XF
The mole ratio of XBr to Br2 is 2:1
Mole of Br2 = mass/molar mass
= 0.7241/159.808
= 0.004531 mole
Mole of XBr = 2 x mole of Br2
= 2 x 0.004531
= 0.009062 mole
Molar mass of XBr = mass/mole
= 1.300/0.009062
= 143.456 g/mol
Since the molar mass of Br is 79.904, the molar of X would be:
143.456 - 79.904
= 63.55 g/mol
Hence, X would be Cu.
More on molar mass calculation can be found here: brainly.com/question/20691135
