Which of the following industrial processes involves a voltaic cell rather than electrolysis?
a. coating forks and knives with silver
b. extracting sodium from sodium hydroxide
c. reinforcing the hull of a ship so that it resists corrosion
d. converting energy stored in chemical bonds to electricity

 D. Converting energy stored in chemical bonds to electricity

D

Explanation:

Edgen. 2020

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

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%