Please help me in Q3 it’s not understandable to me

A- mixture

B- element

C- compound

Explanation:

A mixture is composed of two or more substances. Since it is not entirely homogeneous throughout, then it can not melt or boil at a fixed temperature.

An element is any substance that cannot be decomposed into simpler substances by ordinary chemical processes. This describes substance B.

A pure chemical element has a fixed melting and boiling point.

A compound is composed of one or more chemical elements. A compound may be broken down into its components by certain processes.

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%

> b takes place in the gas phase in an isothermal tubular reactor. the feed is one mole of a per one mole of c, an inert. the entering temperature and pressure are 427°c and 10 atm, respectively. the gas constant r = 0.08206 atm · l/mol · k.