What type of output waveform we get in astable multivibrator circuite using ic 555 if pin no 5 is?

Go to google.com and type "lm555 data sheet". That will get you all knowledge about that ic, with links to other versions. Here is one: www.arrow.com/en/datasheets/140548/rochester-electronics/lm555n

As you can see, or should be able to figure out, pin 5 is one input to a comparator and pin 6 is the other. Connecting either input to Vcc (or to ground) forces the circuit to one or the other state forever.

Here is a free course in basic electronics: www.phy.davidson.edu/instrumentation/NEETS.htm