Redox Reactions

the sum of oxidation states of all elements in a compound is always zero.
(i) Oxidation state of in
(ii) Let oxidation state of


(iii) Let oxidation state of in


(iv) Let oxidation state of in


Increasing order of oxidation states is (i) $

When magnesium (Mg) is burned in air, it produces a very bright, dazzling white flame. This is due to the high temperature at which magnesium burns, emitting a white light that is characteristic of the reaction. Magnesium reacts with oxygen in the air to form magnesium oxide, and the bright white flame is a result of this intense combustion.

Step 1: Understanding the reaction between a base and an amphoteric metal.
The reaction between sodium hydroxide (NaOH), which is a strong base, and zinc (Zn), an amphoteric metal, is a characteristic reaction where the metal reacts with the base to produce a salt and hydrogen gas. Amphoteric metals are elements that can react with both acids and bases. Zinc is a well-known example of an amphoteric metal.
Step 2: Writing the balanced chemical equation.
When zinc reacts with sodium hydroxide solution, it forms sodium zincate (Na₂ZnO₂) and liberates hydrogen gas (H₂). The balanced chemical equation for this reaction is:

 2NaOH(aq) + Zn(s) → Na2ZnO2(aq) + H2(g) 

Step 3: Evaluate the options.

• Option (a): Sodium Zincate and Hydrogen gas: This matches the products of the reaction, as derived from the chemical equation.
• Option (b): Zinc Oxide and Sodium: This is incorrect. Zinc oxide is not formed, and sodium metal is not a product.
• Option (c): Sodium Hydride and Zinc: This is incorrect. Sodium hydride is not formed, and zinc is a reactant, not a product.
• Option (d): No reaction will occur: This is incorrect, as zinc, being an amphoteric metal, readily reacts with strong bases like NaOH.

Step 4: Conclusion.
The reaction between NaOH and Zn produces sodium zincate and hydrogen gas.
Conclusion:

Sodium Zincate and Hydrogen gas

Step 1: Understanding the Whitewashing Process
Whitewashing is a process in which calcium hydroxide (Ca₂OH₂) is used. When it is applied to the walls, it reacts with carbon dioxide from the air and forms calcium carbonate (CaCO₃), which deposits on the surface of the walls. This reaction is represented by:

 Ca(OH)2 + CO2 → CaCO3 + H2O 

Step 2: Conclusion
Thus, the compound deposited on the walls after whitewashing is calcium carbonate (CaCO₃).
Conclusion:

CaCO₃ (Calcium carbonate)

Barium nitrate is a metal nitrate of a group 2 element. Upon heating, metal nitrates decompose to form the corresponding metal oxide, nitrogen dioxide, and oxygen gas.
The general decomposition reaction for group 2 metal nitrates (like Ba(NO ) ) is: Explanation of the products:
BaO: The metal oxide formed from the decomposition of the nitrate.
NO : A brown toxic gas, produced from the breakdown of the nitrate ion.
O : Molecular oxygen released during the decomposition process. Therefore, heating barium nitrate gives: