Is it that 1000 liter to 1 ton?

Answer 1

No. A ton is a measure of mass, and a liter (or litre) is a measure of volume. The two measure different things and can't be converted back and forth to each other in most cases.

They can be converted by the density of the substance, and using one set of units.

A ton is an imperial measure of mass. There is a metric ton, spelt "tonne", which is 1000 kg and is slightly more than a short ton of 2000 lb, slightly less than a long ton of 2240 lb.

A liter is a metric measure of volume.

Density = mass ÷ volume ⇒ mass = density x volume.

As long as you use the correct units, 1000 liters of a substance of the right density will weight 1 ton - it'll be up to you to find the substance, but note that density will depend up on temperature and pressure (the latter having little effect on liquids).