The correct answer is option 'C': chemical and exothermic change.

Explanation:

When magnesium is burnt, it undergoes a chemical reaction with oxygen in the air to form magnesium oxide. This reaction is highly exothermic, meaning it releases heat and light energy. Let's break down the explanation further:

1. Chemical Change:
Burning magnesium involves a chemical change because the magnesium atoms combine with oxygen atoms from the air to form a new compound, magnesium oxide. This chemical reaction is represented by the equation:

2Mg + O2 → 2MgO

The reactants (magnesium and oxygen) are converted into the product (magnesium oxide) with different chemical properties. This transformation is irreversible, meaning it cannot be easily reversed to obtain the original reactants.

2. Exothermic Change:
During the burning of magnesium, a significant amount of heat and light energy is released. This release of energy is characteristic of an exothermic reaction. The energy is released due to the formation of new chemical bonds in the magnesium oxide, which are more stable and have lower energy than the bonds in the reactants.

3. Physical Change:
A physical change involves a change in the physical properties of a substance without the formation of any new substances. Burning magnesium does not merely change its physical state or appearance; it undergoes a chemical reaction, resulting in the formation of a new compound.

4. Reversible Change:
A reversible change refers to a change that can be easily reversed to obtain the original substances. The burning of magnesium is not reversible because the magnesium atoms have combined with oxygen to form magnesium oxide, and it is not feasible to separate them back into their original forms without the use of additional chemical processes.

In conclusion, the burning of magnesium is a chemical and exothermic change because it involves a chemical reaction with oxygen, resulting in the formation of magnesium oxide while releasing heat and light energy.

Burning of of magnesium ribbon in air an example of chemical change this is because when we born magnesium ribbon is presence of oxygen it form magnesium oxide from magnesium oxide we cannot get we cannot get back it back its original state