$Me_3B$,$BH_3$,and $BF_3$ are three Lewis acids. Which one of the following is the correct sequence of these acids in order of their increasing acid strength?

Which of the following statements is true with respect to $H_2O$,$NH_3$ and $CH_4$?
$A.$ The central atoms of all the molecules are $sp^3$ hybridized.
$B.$ The $H-O-H$,$H-N-H$ and $H-C-H$ angles in the above molecules are $104.5^{\circ}$,$107.5^{\circ}$ and $109.5^{\circ}$ respectively.
$C.$ The increasing order of dipole moment is $CH_4 < NH_3 < H_2O$.
$D.$ Both $H_2O$ and $NH_3$ are Lewis acids and $CH_4$ is a Lewis base.
$E.$ $A$ solution of $NH_3$ in $H_2O$ is basic. In this solution,$NH_3$ and $H_2O$ act as a Lowry-Bronsted base and acid respectively.
Choose the correct answer from the options given below:

Which one of the following contains ionic,covalent,and coordinate bonds?

In $O_3$,there are:

Which of the following pairs of molecules is isoelectronic as well as isostructural?

In the solid state,$PCl_5$ exists as.......