What is the correct numerical set up for calculating the atomic mass of si

You determine the weighted averages if the individual isotopic masses.

Procedure:

The atomic mass of Si is the weighted average of the atomic masses of its isotopes.

We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its percent abundance).

The three stable isotopes of Si are Si-28 (27.98 u, 92.22 %), Si-29 (28.98 u, 4.69 %), and Si-30 (29.97 u, 3.09 %).

Set up a table for easy calculation.

0.9222 × 27.89 u = x u

0.0469 × 28.98 u = y u

0.0309 × 29.97 u = z u

         TOTAL =  (x+y+z) u = atomic mass of Si.

the answer is learned

- 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