The correct option is A 0.80 M
Number of moles of HCl dissolved (nHCl)=0.2 mol
And number of moles of Cl− obtained from HCl,
Ncl−=nHCl=0.2 mol
Number of moles of BaCl2 dissolved
(nBaCl2)=0.1 mol
And number of moles of Cl− obtained from BaCl2,
ncl−=2(nBaCl2)=2×0.1=0.2 mol
Thus, total number of moles of Cl− dissolved
=0.2+0.2=0.4 mol
Now molarity=no.of molesVolume(in mL)×1000
=0.4500×1000=0.80 M
Thus, molarity of Cl− ion is 0.80 M.
So, option (D) is the correct answer.