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 it’s B vibrations in molecules
Explanation: The Kinetic Theory of Matter states that matter is composed of a large number of small particles—individual atoms or molecules—that are in constant motion.
The correct answer is (A) from 2nd to 3rd shell.
The explanation :
when a gain of energy is the shift of the electrons from a shell of low energy to the shell of high energy
and we have here 2nd shell is the shell of low energy, and 3rd shell is the shell of high energy.
∴ (A) from 2nd to 3rd shell is the correct answer.
Answer:
C7H603 + CH3OH --> C8H803 + H2O
Balanced equation with corresponding stoichiometric numbers.
Explanation:
the salicylic acid, also called aspirin, when reacting with methanol produced an irreversible reaction giving methyl salicylate and water
<h3><u>Answer;</u></h3>
Phloem
<h3><u>Explanation;</u></h3>
- <u>Club moss</u> plant belongs to the the family Lycopodiaceae, Lycophyte includes any spore-bearing vascular plant.
- <u>Liverworts</u> on the other hand are bryophytes which belongs to the division bryophyta. Bryophytes are small, non-vascular plants which includes mosses, hornworts and liverworts.
- <em><u>Vascular plants contain vascular tissues which play an important role of transportation in plants. </u></em>The major vascular tissues are phloem and xylem. <em><u>Non-vascular plants</u></em> on the other hand lacks the vascular tissues for transportation of substances.