When the salinity of a seawater sample changes, the ratio of the major salt ions does not change?

The Answer is that the statement is true.
Salinity of a seawater sample changes, the ratio of the major salt ions does not change because we can define salinity as it is equal to the salts that are dissolved in seawater and we can expresses salinity as grams of salt per kg of seawater, so the major salt ions concentration in water does not change with the salinity of seawater. We can also determine the salinity by measuring the concentration of chloride ions in seawater.

Adozen is 1221/12 = 1.751.75 x 12 = 21therefore, 1.75 is the answer.