Consider the statement: "copper is a red-brown element obtained from copper sulfide ores by heating the ores in air, which forms copper oxide. heating the copper oxide with carbon produces impure copper, which is purified by electrolysis." how many of these, i) color ii) heating with carbon iii) purification by electrolysis are physical properties or changes?

1, just I) color.

Explanation:

Physical properties are the properties that can be observed without changing the composition of a substance, such as color, temperature, density, and boiling point.

A physical change is a change in the substance that only modifies its aggregation state, such as solidification, and boiling.

Chemical properties are the properties that need a reaction to being observed, such as the combustibility, which needs a combustion reaction to being quantified.

When a chemical reaction occurs, and the composition of the substance change, it's a chemical change.

So, the heating copper with carbon is a chemical reaction, and purification by electrolysis is too. Color is the only physical property.

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%