MCQ
Correct Lewis acidity order of $BX_3$ is
- ✓$BF_3 < BCl_3 < BBr_3 < BI_3$
- B$BF_3 > BCl_3 > BBr_3 > BI_3$
- C$BCl_3< BBr_3 < BI_3 < BF_3$
- D$BF_3 < BI_3 < BBr_3 < BCl_3$
(ii) Size of halides increase down the group, hence the ability of back bonding decreases making the molecule more acidic.
Hence, correct order of Lewis acid for boron-halides is $\mathrm{Bl}_{3}>\mathrm{BBr}_{3}>\mathrm{BCl}_{3}>\mathrm{BF}_{3}$
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$(a)\,0.075\,\,M\,CuS{O_4}$ $(b)\,0.060\,\,M\,(NH_4)_2SO_4$
$(c)\,0.14\,\,M\,urea$ $(d)\,0.04\,M\,MgCl_2$
[Molar mass of $\mathrm{KCl}=74.5$ ]

