The reaction that has the greatest tendency to be reversed in an spontaneous redox reaction is that whose forward standard reduction potential is the lowest (mos negative) one because that means that the reversed reaction will have the highest (most positive) standard reduction potential.
So, the answer is Cr(3+) + 3e- ---> Cr(s) with Eo = -0.91 V, whose reversed reaction is Cr(s) - 3e- ---> Cr (3+) with Eo = +0.91 V.
Answer: the second option Cr(3+) + 3e- ---> Cr(s) Eo = -0.91 V
Bases- soap, baking soda
Acids- oranges,lemons
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Mass of Oxygen required : 24 grams
<h3>Further explanation</h3>
Given
3 moles of H
1.5 moles of O
3 moles of H₂O
Required
Mass of O
Solution
Reaction
2H₂ + O₂ ⇒ 2H₂O
Mass of Oxygen for 1.5 moles of O :
= mol x Ar O
= 1.5 moles x 16 g/mol
= 24 grams