Answer:
A. there is an isotope of lanthanum with an atomic mass of 138.9
Explanation:
By knowing the different atomic masses of both Lanthanum atoms, we can not tell anything about their occurence in nature. Therefore, all the last three options are incorrect. Because, the atomic mass does not tell anything about the availability or natural abundance of an element.
Now, the isotopes of an element are those elements, which have same number of electrons and protons as the original element, but different number of neutrons. Therefore, they have same atomic number but, different atomic weight or atomic masses.
Hence, by looking at an elements having same atomic number, but different atomic masses, we can identify them as isotopes.
Thus, the correct option is:
<u>A. there is an isotope of lanthanum with an atomic mass of 138.9.</u>
A magical or medicinal potion/solution
Answer:
2HCl is the product of this reaction 2 is added in order to balance the reaction
The animals have to adapt to their new environment meant and continue mating so they do not go extinct
Soil
profile
Soil
profile is the vertical sequence of the layers of soil. Furthermore, there are
actually six layers of the soil which involves the organic matter, -where most
humus is present-, surface soil, the subsoil, the parent rock, and the bedrock
as the innermost and core layer of the soil. In addition each soil layer has
three to four soil horizon. These horizons are the physical features of the soil,
mainly the texture, color and composition.
