Metal M: Manganese (Mn)
Black Colored Product: Manganese(IV) oxide (MnO2)

Reaction of Manganese with Oxygen:
Manganese is a transition metal that readily reacts with oxygen to form various oxides. In this case, the metal M is manganese, and it reacts with oxygen to give a black-colored product known as manganese(IV) oxide.

1. Characteristics of Manganese:
Manganese is a silvery gray metal that is commonly found in nature as a mineral in combination with other elements. It is a hard and brittle metal with a high melting point and is known for its oxidation states ranging from +2 to +7. It is widely used in various industries, including metallurgy, chemistry, and medicine.

2. Reaction with Oxygen:
When manganese reacts with oxygen, it undergoes oxidation, resulting in the formation of manganese oxide. The specific reaction involved is the combination of manganese with oxygen gas (O2) to form manganese dioxide (MnO2).

2Mn + O2 → 2MnO2

3. Formation of Manganese(IV) Oxide:
The reaction between manganese and oxygen produces manganese(IV) oxide, also known as manganese dioxide. MnO2 is a black-colored solid compound that has a crystalline structure. It is insoluble in water and does not dissolve in acids.

4. Role of Oxygen:
Oxygen is a highly reactive element that readily combines with other elements to form oxides. In the case of manganese, it reacts with oxygen to form manganese dioxide. This reaction is an example of an oxidation reaction, where manganese undergoes an increase in its oxidation state from +2 to +4.

5. Significance of Black Color:
The black color observed in the product, manganese(IV) oxide, is due to the presence of manganese ions in the +4 oxidation state. The compound absorbs most of the visible light, giving it a black appearance.

Conclusion:
In summary, the metal M in this scenario is manganese (Mn), which reacts with oxygen to form manganese(IV) oxide (MnO2). The reaction involves the combination of manganese with oxygen gas, resulting in the formation of a black-colored solid compound. This reaction is an example of an oxidation reaction, where manganese undergoes an increase in its oxidation state. Manganese dioxide is insoluble in water and does not liberate hydrogen from acids.

The metal M is Copper The black colour product is copper oxide The reaction is :2Cu+O2 =2CuO