Question

Which one of the following pentafluorides cannot be formed?

• A. $P{F}_5$
• B. $As{F}_5$
• C. $Sb{F}_5$
• D. $Bi{F}_5$

Answer 1

Answer: (D)

$B{i}^{5+}$ has lower stability than $B{i}^{3+}$ due to inert pair effect. Hence, $Bi$ forms trihalides rather than pentahalides.