<span>40 20Ca this is the appropriate symbol for an isotope of calcium-42 corresponding to the isotope notation AZX</span><span />
Just 2 valence electrons.
Hydrogen already has one to start with, as well. With the exception of hydrogen and helium, all other atoms need 8 valence e-
Its hybridization would be sp because Be only has 2 covalent bonds with Cl
Here’s the math for your answer, which is 3.3 L HCl