Redox Reactions

Step 1: Understanding the Formula.
For a radioactive substance, the formula for half-life is given by: Where and the remaining percentage is 80%.
Step 2: Calculation.
Substitute the values into the formula: Thus, the correct answer is (B).

Step 1: Understanding the Reaction.
The reaction involves the stoichiometry of the reaction between A, B, C, and D. The rate law should match the correct stoichiometric coefficients.
Step 2: Analyzing the Options.
- (A) does not match the stoichiometry of the reaction.
- (B) does not match the stoichiometric coefficients.
- (C) is incorrect.
- (D) matches the stoichiometric coefficients, making it the correct answer.
Step 3: Conclusion.
The correct answer is (D) .

Step 1: Understanding the Compounds.
The compound contains manganese in the +3 oxidation state (since fluoride is typically -1). Similarly, has manganese in the +3 oxidation state, as oxygen is -2.
Step 2: Analyzing the Options.
- (A) Mn in +2 is incorrect for this reaction.
- (B) Mn in +3 is the correct answer because both and have Mn in the +3 oxidation state.
- (C) Mn in +4 is not correct for this reaction.
- (D) Mn in +5 is also incorrect.
Step 3: Conclusion.
The correct answer is (B) Oxidation state of Mn is +3.