Questions about bonds

I have 4 questions that i need to know for each bond.

1) The number of bonding electron pairs on central atom?
2) The number of non bonding electron pairs on central atom?
3) Name of the molecular geometry?
4) What are the bond angles? (in degrees)


NO2^-

NH4^+

HCN

SF4

XeF4

NO2-
1) 3 bonding electron pairs on the central atom, which is nitrogen (double bond to one oxygen, single to the other oxygen)
2) 1 pair of nonbonding electron pairs on Nitrogen
3) Bent
4) 120º

NH4+
1) 4 bonding electron pairs on the central atom, which is Nitrogen (four single bonds to four Hydrogens)
2) No unbound electron pairs on the Nitrogen
3) Tetrahedral
4) 109.5º

HCN
1) 4 bonding electron pairs on the central atom, which is Carbon (triple bond to Nitrogen, single bond to Hydrogen)
2) No unbound electron pairs on Carbon (one electron pair on the Nitrogen though)
3) Linear
4) 180º

SF4
1) 4 bonding electron pairs on the central atom, which is Sulfur (single bonds to 4 Fluorides)
2) 1 unbound electron pair on the central atom (Sulfur has 6 valence electrons, leaving two unpaired)
3) Trigonal bypyramidal (seesaw)
4) 90, 120 and 180º

XeF4
1) 4 bonding electron pairs on the central atom, which is Xenon (single bonds to 4 Fluorides)
2) 2 unbound electron pairs on the central atom
3) Square planar
4) 90 and 180 º