What is the hybridization of sulfur in $SO_2$?

The electronic structure of molecule $OF_2$ is a hybrid of

The structure of $IF_{7}$ is

Consider the following species: $BrF_5, XeF_5^-, BF_4^-, ICl_4^-, XeF_4, SF_4, NH_4^+, ClF_3, XeF_2, ICl_2^-$. Number of species having $sp^3d$ hybridized central atom is . . . . . . .

$XeF_4$ is square planar whereas $CCl_4$ is tetrahedral because

What is the decreasing order of carbon-carbon single bond length in the following compounds?
$(I) CH_2 = CH - C \equiv CH$
$(II) CH \equiv C - C \equiv CH$
$(III) CH_3 - CH = CH_2$
$(IV) CH_2 = CH - CH = CH_2$