How many liters are in a tonne?

That depends on the density of what you are measuring. To work out questions like this you need to use the equation density*volume = mass Let's assume it is water with a density of 1kg per litre. So a 1000kg (a tonne) would be 1000 litres Let's now assume it is iron with a density 7.86kg per litre. So 1000kg would be 1000/7.68 = 127 litres. To work out questions life this you need to use the equation density*volume = mass

Doesn't work like that.

Liters is a unit of volume, while tonne is a unit of weight.

How many liters you get to a tonne depends on the density of the substance.

If you use popcorn, you'd need a lot more liters to make a tonne than if you used sand.

The litre is a measure of volume. The tonne is a measure of mass. The two are not interchangeable without further knowledge (i.e. density).
As the robot on "Lost in Space" has been known to say in such cases, "It does not compute." In other words: There is no relationship between the units of volume, like liters, and the units of weight, such as tons. You need to add what the material is that you want t measure. Example: How many liters of substance X equals a ton?

Not possible to convert from a mass measure to a volume measure without knowing the medium density.