[ifrah]

how are aliphatic hydrocarbons having both double and triple bonds are named according to iupac?

[cth]

You can go to http://old.iupac.org/nomenclature/, click on ACD/IUPAC Name, draw your molecule and get the name.

It is a free on-line naming program with some limitations on the maximum number of atoms,. but very useful nonetheless. 

[Schrödinger]

Thanks cth, that's an awesome link you posted. Super-helpful!
Here's your mole snack

[ifrah]

is there anyother answer to it?

[Schrödinger]

A double bond is always given more preference in numbering (i.e, it gets the lower number) over a triple bond, except in one case.

I leave it to you to explore and find out what that case is...please see the link posted by cth.

It's a lot of fun and a good self-learning experience. I'm pretty sure you'll learn a lot more  there than posting questions on the forum.

[ifrah]

all this fine but i have certain difficulties in drawing

[Schrödinger]

The applet is quite user friendly to draw in...unless you have some problems with your computer.

What difficulties are you experiencing?

[ifrah]

i am unable to draw double bonds in it or dont know how to draw them

[cth]

i am unable to draw double bonds in it or dont know how to draw them

Once you have drawn a single bond:
Click once on the middle of it. It should make a double bond.
Click a second time, you should get a triple bond.
Third click, you go back to a single bond.
And so on...

[ifrah]

thnkx a lot