MCQ
The amine with lowest $pK _{ b }$ is :
- A$CH _3 NH _2$
- ✓$\left( CH _3\right)_2 NH$
- C$\left( CH _3\right)_3 N$
- D$C _6 H _5 NH _2$
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$P =\left[ FeF _6\right]^{3-}, Q =\left[ V \left( H _2 O \right)_6\right]^{2+} \text { and } R =\left[ Fe \left( H _2 O \right)_6\right]^{2+} \text {. }$
The correct order of the complex ions, according to their spin-only magnetic moment values (in $B.M.$) is

