How many grams is 1 liter?

Answer 1

Only 1 Liter of water weighs 1000 grams.
In converting weight or mass to capacity, it depends on what consistency it is at.
Grams is a unit measurement of mass, and liters are a unit measurement of volume. You cannot mix the two units, since it depends on the substance (water, liquid Mercury, etc.). Each substance has a certain density. The density of a substance changes with temperature and pressure.

The standard temperature 20oC and the standard pressure of 1013.25 hPa is used when comparing substances, except for water, because water reacts otherwise than other substances.

Ex.:

Mercury has a weight of 13600 g at 20oC 1 1013.25 hPa

Water has weight of 997 g at 20oC 1013.25 hPa

So one litre of pure water is defined as one kilogram at 3.8oC 1013.25 hPa.