How many protons and neutrons are in an atom with this representation:
27 ?
17
which element would have this representation:
43 ?
21
if a neutral atom gains 4 electrons, its charge will be…

Explanation:

There isn't any set number of isotopes an atom can have. As the number of neutrons in an atom increases or decreases, the isotopes tend to become more and more unstable until they get to the point where they decay faster than neutrons can change. According to the International Atomic Energy Agency, Mercury currently has the most at 45 identified isotopes.

- 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