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>
D
Molecules consist of multiple atoms put together to create a new form.
Answer:
(a) Eka-aluminum and gallium are two names of the same element as Eka-Aluminium has almost exactly the same properties as the actual properties of the gallium element. The properties: atomic mass, density, melting point, formula of chloride and formula of oxide are almost the same.
Explanation:
Scandium - Eka boron.
(ii) Gallium - Eka aluminium.
(iii) Germanium - Eka silicon.
Hey there!!
A lawn mower works by converting chemical energy (energy stored in the gas) to mechanical energy.
Hope this helps you and have a great day!!!! I wish you the best of luck (:
Involuntary and the brain, because the stem controls involuntary reactions
