Q. why does ammonia act as a complexing agent.

A:  N: has a lp. can act as ligand.

 

Q:  why nitrogen exist as N2 but phosphorous a P4

A:  nitrogen can form only P pi - P pi bonds. due to absence of d orbitals.

     Phosporous due to vacant 3d orbital can form d pi- p pi bonds.

     thereby extend co ordination number.

 

Q: Why boiling point decreases decreases down a group?

A:  hydrogen bonding decreases down a group.

 

hydrogen bonding can also be used to explain why H2O is liqiud. H2S is gas.