Which particles contribute to the atomic number and why ??

the number of protons in the nucleus that are found in an atom is what determines an element's atomic number.why you may ask and thats because Protons contribute to the mass of an atom.(along with neutrons but they dont have a charge)but protons provide a positive charge to the nucleus.  

Explanation:

because the atom is electrically neutral, the number of electrons must equal the number of protons.

true

explanation:

- 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