Is a change in matter that produces one or more substances Chemical change
Physical change
Chemical reaction

Chemical change

Explanation:

A chemical change happens when one chemical substance is transformed into one or more different substances, such as when iron becomes rust. Chemical changes occur through the process of chemical reactions, and the resulting substances have different properties because their atoms and molecules are arranged differently.

its not physical change: What is a physical change? A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.

its not chemical reaction: A chemical reaction is a process in which one or more substances, also called reactants, are converted to one or more different substances, known as products.  A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products

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8 carbon atoms forming single bonds with 18 hydrogen atoms; a triple bond exists between the third and fourth carbon atom from the right

explanation:

they are made of gases.

they have a spherical shape.

they make energy through fusion.