Final answer:
The correct answer is option C. one large orange circle attached to two small white circles.
Step-by-step explanation:
Leandra is drawing a model of a chemical reaction. On one side of the arrow, she has a large orange circle (representing one type of molecule) by itself, which we can symbolically write as 'A', plus two small white circles attached to each other (representing a molecule of diatomic element, probably 'B2'). To complete the model on the other side of the arrow, Leandra should draw a product that reflects the atoms recombined into a new structure. This means the most likely answer is one large orange circle attached to two small white circles (choice C), which would represent a single molecule combining one 'A' atom and two 'B' atoms, possibly 'AB2'. This shows that all the original atoms from the reactants are accounted for in the product, suggesting that matter has been conserved during the reaction.
A balanced chemical equation for the reaction could resemble 'A + B2 → AB2'. Plus signs (+) separate individual reactant and product formulas, and an arrow (→) points from the reactants to the products to indicate the direction of the reaction. This equation also shows a standard way of writing chemical equations, with reactants on the left and products on the right. By counting the number of atoms on each side, we can confirm that the equation is balanced, which is a fundamental principle of chemical reactions. If Leandra includes state symbols in her diagram, it would provide additional information about the physical states of the reactants and products.