I want to make a digital clock, suggest me which is the preferable BCD IC for that and also a comparison of asynchronous and synchronous digital clock, which is more preferable?

 

Depending on what you mean by "digital clock" synchronous or asynchronous doesn't make sense. By synchronous means clocked and references how data us transmitted and not keeping time.

But as inn your other post you aren't putting in any effort of what you want to do.
http://forum.allaboutcircuits.com/showthread.php?p=552644#post552644
http://forum.allaboutcircuits.com/showthread.php?p=552628#post552628

If you expect others to help then you are expected to help others help you.

 

There is always this thread. Not quite ready for prime time, but getting there.

Digital Clock