1 kg is equal to how many liter

Geno and anon are of course correct.  

I am just going to look at WATER

1 litre of WATER weighs 1Kg.        

plus    

The rest is not just for water it is for any fluid

a cube that has sides 10cm will hold 1 litre of water.

$$10*10*10=1000cm^3\\



1 litre \equiv 1000cm^3 \equiv 1000ml

therefore

1cm^3\equiv 1ml$$

It is really handy to remember this.

Kg is a measure of weight and liter is a measure of volume.

Kilograms measure mass; liters measure volume.

So, if you want to know how many kilograms are in a liter, you must specify what you are talking about: iron, water, air, etc.