A chemist burns 160.0 g of Al in excess air to produce aluminum oxide, Al2O3. In the experiment she producds 260.0 g of solid aluminum oxide. The balanced chemical equation is: 4 Al + 3 O2  2 Al2O3 a. Determine the theoretical yield. b. Determine the percent yield. 4. In the reaction of Zn with HCl, 140.15 g of ZnCl2 was actually formed, although the theoretical yield was 143 g. What was the percent yield? 5. 12.5 g of copper are reacted with an excess of chlorine gas, and 25.4 g of copper(II) chloride are obtained in the experiment. Calculate the theoretical yield and the percent yield. Cu + Cl2  CuCl2

- 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

the answer is c. nacl

since electrons are negative the answer is neagtaive