500 ml. If it is water at room temperature, it is what people call 1 kg. That is, 0.5 kg.

If it is wine, it is 0.47 kg.

If it's milk, it's similar to water and heavier. 0.55 kg.

If it is vinegar, it is 0.58 kg.

If it is soy sauce, it is 0.6 kg.

If it is kerosene, gasoline, diesel and the like, it also varies according to the density (or specific gravity). Generally between 0.8 and 0.9 kg.