Which atom has a change of oxidation number of +4 in the pictured redox reaction?
a. K
b. Cr
c. O
d. S

The answer to your question is the letter d. S

Explanation:

Data

Change of +4 in the oxidation number

Chemical reaction

               K₂Cr₂O₇  +  H₂O  +  S  ⇒   KOH  +  Cr₂O₃  +  SO₂    

Process

1.- Calculate the oxidation numbers following the rules.

Some rules

  H = +1       O = -2    Alkali metals = + 1    Alkali earth metals = +2    

K₂⁺¹Cr₂⁺⁶O₇⁻²  +  H₂⁺¹O⁻²  +  S⁰  ⇒   K⁺¹O⁻²H⁺¹  +  Cr₂⁺³O₃⁻²  +  S⁺⁴O₂⁻²    

Elements that changed their oxidation numbers

                       Cr₂⁺⁶   Cr₂⁺³

                       S⁰       S⁺⁴

the answer is minerals.

hurricanes form when warm, moist air from the ocean surface quickly rises into the atmosphere and forms storm clouds and rain. when the clouds are formed, heat is released which warms the cool air in the upper regions of the atmosphere so that the cycle can continue. which two phases of the water cycle are repeated in this process?