Explain the following observations:
(a) HNO3 is a stronger oxidizing agent than H3PO4.
(b) Silicon can form an ion with six fluorine atoms, SiF62-, whereas carbon is able to bond to a maximum of four, CF4.
(c) There are three compounds formed by carbon and hydrogen that contain two carbon atoms each (C2H2, C2H4, and C2H6), whereas silicon forms only one analogous compound (Si2H6).