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>
Answer:
D. Increase in UV radiation
Explanation:
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Answer:
Explanation:
Hello!
In this case, since the molarity of a solution is calculated by diving the moles of solute by the volume of solution in liters, we first compute the moles of barium hydroxide in 35.5 g as shown below:
Then, the liters of solution:
Finally, the molarity turns out:
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The answer is c because thats the number when combined with a metal. +1 is when its combined with a nonmetal.
Explanation:
In the context, a vial which is used in store medical samples is filled with water at room temperature. And the vial is kept on a cold water. Also a water bag containing warm water is kept near the vial.
The cold water kept at the bottom of the vial is having lower kinetic energy while warm water will have higher kinetic energy than the others. Since the water in the vial is at room temperature and it is in touch with the cold blue water, the water in the vial will loose or give its temperature to the cold blue water through conduction as well as convection process since temperature always flows from a hot body towards the cold body.
On the other hand, the warm water placed next tot he vial will give its temperature to the atmosphere.
