If both the first and second shells of an atom are full, what is the total number of electrons present in that atom?

10

Explanation:

the capacity for each shell for the first 20 elements can be given by

2.8.8.2

2 electrons in the first shell

8 in the 2nd and in the 3rd

and 2 in the 4th

so if both the first and 2nd shells are full,

2+8=10 electrons

petroleum? coal maybe?

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms