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>
The Benzenesulfonic acid does not undergo Friedel-Crafts alkylation because of the deactivation of the compound by the carboxylic group.
<h3>What is the Grignard reagent?</h3>
The Grignard reagent is a compound that contains alkyl magnesium halide.
a) The student will be unsuccessful to prepare a Grignard reagent from 4-bromocyclohexanol because of the -OH group that reacts with the Grignard reagent when formed.
b) The Benzenesulfonic acid does not undergo Friedel-Crafts alkylation because of the deactivation of the compound by the carboxylic group.
c) The compound (2S, 3R)- 2,3-Dibromobutane has a specific rotation, [a]D, 0⁰ because it is a meso compound.
d) This is because, the tertiary alkyl halide is more prone to elimination reaction giving the alkene.
e) This is because, the reaction may be occurring by an SN1 mechanism and the rate determining step is the formation of the carbocation.
Learn more about substitution reaction:brainly.com/question/16811879
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Not sure but it might be A or B
The correct answer is that last one
1000 to the power 4 not so good at math but
