Answer:
10.4
Explanation:
-log(4.2x10^-11) = 10.37 = 10.4
The number 4 in the 4/2He indicates the atomic mass number of helium.
Answer: Option 3
<u>Explanation:
</u>
The elements present in periodic table generally represented as
. Here X will be the element in the periodic table, A is the atomic mass number of the element X and Z is the atomic number of the element X.
So, the number 4 is the atomic mass number of He and He-4 is the stable isotope of helium which can also be termed as alpha particle.
Mass number = number of protons + neutrons count.
Thus the number 4 denotes the Helium's atomic mass number.