Answer:
D
Explanation:
In a Helium (He) atom, the atomic structure of the atom has 2 protons, 2 electrons and 2 neutrons. For an element X to be a Helium (He) atom, it must possess 2 protons. The number of neutrons present will determine its stability either if its probably radioactive or a natural occurring inert gas.
In option 1,
We have H-2. The symbol "H" is used to denote the element hydrogen in the periodic table and hydrogen has only 1 protons and 1 neutron making its mass number 2.
Option 2,
He -2 : here in this option, we have a helium atom, but with mass number of 2 only. Judging from the formula of mass number = protons + neutrons, we already have proton as 2, hence the number of neutrons there is zero (0)
Option 3,
He - 3 : just like in option 2, the only difference here is that the mass number is 3 hence making the number of neutrons just 1.
Option 4,
He - 4 : This option met the requirements of having 2 protons and 2 neutrons making a total of 4 which corresponds to the mass number.
Beryllium Oxide has a molecular formula Be-O
% covalent character in Be-O = 100 - % ionic character in Be-O
Now,
% ionic character = {1 - exp[(-0.25)(E(Be)-E(O))²]}*100
where,
E(Be) and E(O) are the electronegativity values of Be and O
Based on the Paulings scale:-
E(Be) = 1.57
E(O) = 3.44
% ionic = {1 - exp[(-0.25)(1.57-3.44)²]}*100 = 58.28%
Therefore, % covalent = 100 -58.28 = 41.72%
Ans: b) 41 percent
