`sp^(3)` hybridisation is involved in `CH_(4), H_(2)O and NH_(3)`. Why are the bond angles different in three cases?

The bond angles in molecules H_(2)O, NH_(3), CH_(4) and CO_(2) are in the order :

Bond angle in (CH_(3))_(3) N is little more than the bond angle in NH_(3) . Explain.

Oxidation number of C in CH_(3)OH,CH_(2)O,COOH and C_(2)H_(2) is respectively :

The d-orbitals involved in sp^(2)d and sp^(3)d^(2) hybridisation are respectively :

The O-O -H bond angle in H_(2)O_(2) is

i) Write IUPAC name of CH_(3)CH_(2)NH_(2) . ii) Arrange the following amines in the order of their increasing basic strength in aqueous solution. (CH_(3))_(3)N_(1), (CH_(3))_(2)NH_(1), CH_(3)NH_(2) .

b) What is Hinsberg's reagent? Between CH_(3)NH_(2) and C_(6)H_(5)NH_(2) which is more basic?