The mass of a liter of water is: 1 l×1g/cm3 =1g/cm3 =1000g, that is, a liter of water is equal to 2 kg, water is liquid, and the density of water decreases with the increase of temperature.

The mass of an object is equal to the volume multiplied by the density, which is the mass per unit volume of a substance. If two conditions are known, they can be converted into each other according to the formula that mass is equal to the density multiplied by the volume.

Density is a measure of mass in a specific volume. In the International System of Units and China's legal units of measurement, the unit of density is kg/m3. Density is equal to the mass divided by the volume of an object, indicating the ratio of mass to volume of a certain substance.

Density is one of the characteristics of substances. Every substance has a certain density, and the density of different substances is generally different. Therefore, we can use density to identify substances, and we can identify what substances an object is made of according to its density.

Scientific principles:

Water (chemical formula H2O) is an inorganic substance composed of two elements, hydrogen and oxygen. It is nontoxic and drinkable. Transparent liquid, which is colorless and odorless at normal temperature and pressure, is called the source of human life and an important substance to maintain life, also called hydrogen oxide.

Water is one of the most common substances on the earth, and 71%of the earth's surface is covered with water. It is an important resource for all life, including inorganic compounds and human beings, and it is also the most important component of organisms.

Pure water has very weak conductivity and belongs to extremely weak electrolyte. Water in daily life has more anions and cations because it dissolves other electrolytes, so it has obvious conductivity.