The structure of $NH_3$ is:

The bond angles $b_1, b_2, b_3$ in the above structure of $Al_2Cl_6$ are respectively (in $^{\circ}$):

Which molecule $AX_3$,$AX_4$,$AX_5$,$AX_6$ is most likely to have a trigonal bipyramidal structure if $A$ has no lone pair?

Which of the following molecules can be represented as $AB_2E_2$,where $A$ is the central atom,$B$ represents bond pairs of electrons,and $E$ represents lone pairs of electrons?

Which one of the following compounds has the smallest bond angle?

$AB_{3}$ is an interhalogen $T$-shaped molecule. The number of lone pairs of electrons on $A$ is $......$.