When repeated measurements of the same quantity are very close to one another they are

When repeated measurements of the same quantity are very close to one another they are termed as precise measurements.

Explanation:

An experiment is repeated two to three times and the outcomes were checked to have similar values to attain precision of the measurements. The accuracy and precision are the important in attaining correct measurements.

The accuracy is the closest true value obtained from the measuring instrument. But to get precise results, the measurements were taken repeatedly and then analyzed whether the values obtained are similar or varying significantly.

If the repeatedly measured values are very close to one another that means the measured quantities are precisely taken. All the values are precise in nature.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%