State whether the following statement is true or false:
In water,the ratio of the mass of hydrogen to the mass of oxygen is always $1:8$,regardless of the source of water.

(TRUE) The statement is True.
According to the Law of Constant Proportions,a chemical compound always consists of the same elements combined in the same fixed proportion by mass,irrespective of the source from which it is obtained.
In a water molecule $(H_2O)$,the atomic mass of hydrogen is $1 \text{ u}$ and oxygen is $16 \text{ u}$.
Since there are two hydrogen atoms,the total mass of hydrogen is $2 \times 1 = 2 \text{ u}$.
The mass of one oxygen atom is $16 \text{ u}$.
The ratio of the mass of hydrogen to the mass of oxygen is $2:16$,which simplifies to $1:8$.