The reaction of sodium peroxide and water produces sodium hydroxide and oxygen gas. the following balanced chemical equation represents the reaction.

2 na^2o^2(s) + 2 h2o(l) → 4 naoh(s) + o^2(g)

if 15.7 moles of sodium hydroxide are produced, how many moles of o2 will be made?

3.925 mol.

Explanation:

2 Na₂O₂(s) + 2 H₂O(l) → 4 NaOH(s) + O₂(g) ,

It is clear that 2 moles of Na₂O₂ react with 2 moles of H₂O to produce 4 moles of NaOH and 1 mole of O₂ .

Using cross multiplication:

4 moles of NaOH produced with → 1 mole of O₂ .

15.7 moles of NaOH produced with → ??? mole of O₂ .

∴ The no. of moles of O₂ made = (1 mole)(15.7 mole)/(4 mole) =  3.925 mol.

- 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