I think answer is
C. Something that can be observed or measured while changing the identity of the substance
Answer:
have the same number of atoms of each element in the reactants and in the products
Explanation:
<em>The basic principle in balancing a chemical equation would simply be to have the same number of atoms of each element in the reactants and in the products.</em>
<u>A balanced chemical equation is one that has the same number of atoms of each element on the reactant and the product's side of the equation.</u> For example, consider the equation below:

On the reactant's side, there are 2 atoms of H and O while there are 2 atoms of H and 1 atom of O on the product's side. This is an imbalanced equation. In order for it to be balanced, the number of atoms of H and O on the reactant side must be equal to the number of H and O on the product side as below.

Answer:
Los pulmones y el aparato respiratorio nos permiten respirar. Permiten la entrada de oxígeno en nuestros cuerpos (inspiración o inhalación) y expulsan el dióxido de carbono (expiración o exhalación). Este intercambio de oxígeno y dióxido de carbono recibe el nombre de "respiración"
La función del aparato respiratorio es mover dos gases: <em>el oxígeno y el dióxido de carbono</em>
Explanation:
Answer:
A vascular plant is any one of a number of plants with specialized vascular tissue. The two types of vascular tissue, xylem and phloem, are responsible for moving water, minerals, and the products of photosynthesis throughout the plant.
Explanation:
Answer:
Two electrons fit in the first shell out from the nucleus and eight fit in the second. Every element with more protons than the two of Helium needs to work on shells outside the first one. one you get to ten, you have filled the first two shells.
In a water molecule, oxygen forms one covalent bond with EACH of TWO hydrogen atoms. As a result, the oxygen atom has a stable arrangement of 8 valence electrons. Each hydrogen atom forms only one bond because it needs only two electrons to be stable.