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>
I think the correct answer from the choices listed above is option D. The net ionic equation that will describe the reaction of the reactants when mixed is expressed as:
<span>2PO43–(aq) + 3Ca2+(aq) → Ca3(PO4)2(s)
</span>
Hope this answers the question. Have a nice day.
Answer:
Heat or electricity in the atmasphere
Explanation:
Answer:
1.1 M
General Formulas and Concepts:
- Molarity = moles of solute / liters of solution
Explanation:
<u>Step 1: Define variables</u>
1.2 mol KCL
1.1 L of solution
M = unknown
<u>Step 2: Solve for Molarity</u>
- Substitute: M = 1.2 mol/1.1 L
- Evaluate: M = 1.09091
<u>Step 3: Check</u>
<em>We are given 2 sig figs. Follow sig fig rules.</em>
1.09091 M ≈ 1.1 M
