Answer:
d orbitals
Explanation:
Transition metals are generally known as d-block elements. The electronic configuration of all transition elements finish in a d-orbital weather they are first row, second row or third row transition elements. This is the thread that holds all the elements of the transition series together.
This is why elements of the transition series are generally called the d-block elements.
The molar mass of Sb2S3 is approximately equal to 339.7 g/mol. We calculate the number of moles of Sb2S3 by dividing the given mass by the molar mass.
n = 23.5 g / (339.7 g/mol)
n = 0.0692 mols
To calculate for the number of formula units, we multiply the number of mols by the Avogadro's number,
number of formula units = (0.0692 mols)(6.022 x 10^3)
= 4.167 x 10^22 formula units
You would have to go to sephora and check it out
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>