2ag + h2s ➞ ag2s + h2 according to the equation for this chemical reaction, what does the 2 in front of 2ag tell us? a) two atoms of silver are lost in this reaction. b) two atoms of silver are produced by this reaction. c) two atoms of silver are needed to complete the reaction. d) two atoms of silver are gained to produce silver sulfide

The correct answer is C)  Two atoms of silver are needed to complete the reaction.

Explanation:

The Law of Conservation of Matter postulates that "the mass is not created or destroyed, only transformed." This means that the reagents interact with each other and form new products with physical and chemical properties different from those of the reagents because the atoms of the substances are ordered differently. But the amount of matter or mass before and after a transformation (chemical reaction) is always the same, that is, the quantities of the masses involved in a given reaction must be constant at all times, not changing in their proportions when the reaction ends.

Then, taking into account the Law of Conservation of Matter, as an atom cannot be created or destroyed in a chemical reaction, the number of atoms that are present in the reagents has to be equal to the number of atoms present in the products.

For this, the chemical equation must be balanced. For that, you must first look at the subscripts next to each atom to find the number of atoms in each compound in the equation. If the same atom appears in more than one molecule, you must add its quantities. On the other hand, the coefficients located in front of each molecule indicate the amount of each molecule for the reaction. This coefficient can be modified to balance the equation, just as you should never alter the subscripts. By multiplying the coefficient mentioned by the subscript, you get the amount of each element present in the reaction.

In this case:

Left side: 2 silver  (Ag), 2 hydrogen (H) and 1 sulfur (S)

Right side: 2 silver  (Ag), 2 hydrogen (H) and 1 sulfur (S)

In this case the equation is balanced because you have the same amount of all the elements on each side of the reaction. And the 2 in front of 2Ag indicates that,since silver is a reagent, two atoms of silver are needed to complete the reaction. (option C).

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.