Match each species on the left to a description on the right. Al I2 O2 Cr
1) oxidizing agent
2) reducing agent

Explanation:

I₂ + 2 e = 2I⁻

I₂ converts itself into I⁻ by accepting electron . In this process it increases the oxidation number of element from which it takes electron . Hence it is an oxidizing agent .

Similarly O₂ is also an oxidizing agent .

O₂ + 4e = 2O⁻²

Al is a reducing agent .

Al = Al⁺³ + 3 e

Al gives 3 electrons to other element whose oxidation number is reduced . Hence it is reducing agent .

Similarly Cr is also a reducing agent .

Cr = Cr⁺³ + 3 e .

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%