Which is the correct sequence in the following properties. For the correct order mark `( T)` and for the incorrect order mark `( F) :`
`{:((a)"Acidity order ":SiF_(4) lt SiCl_(4) lt SiBr_(4) lt Sil,,(b)"Melting point":NH_(3) gt SbH_(3) gt AsH_(3) gt PH_(3),,),((c )"Boiling point " :NH_(3) gt SbH_(3) gt AsH_(3) gt PH_(3),,(d)"Dipole moment order ":NH_(3) gt SbH_(3) gt AsH_(3) gt PH_(3),=,5):}`

Options

A. `F T F T`
B. `T F T F`
C. `F F T T `
D. `F F T F`

Answer

A

Explanation

`(a) (F),` As the size of halogen atom increases crowding on Si atom will increases, hence, tendency of attack of Lewis base decreases.
`(b)(T), M.P.` of `NH_(3)` is highest due to intermolecular `H-` bonding in it.
Next lower `M.P.` will be of `SbH_(3)` follofwed by `AsH_(3)` due to high mol. wt. of `SbH_(3)`.
(c) (F) `M.P.` and `B.P.` of increase from `PH_(3)` to `AsH_(3)` due to increase in mol. wt. `NH_(3)` does not follow this trend due to iner molecular H-bonding.
(d) (T), Value of bond moment decreases.