Me pls someone give me the answers to the self-check! 1-5

3 and 5 do not make sense, but I can answer the rest.

1. Reactants are on the left side, and the products are on the right side. Reactants, hence the name, react to form products. So the Cd(NO3)2 compound and the H2S compound are reactants, and the ones on the other side are products.

2. The little letters in parentheses tell you the state of matter. (s) is solid, (aq) is aqueous, (l) is liquid, and (g) is gas.

4. The law of conservation of mass is important, because in reactions mass never disappears just like energy. Mass is never created or destroyed. Mass does not randomly appear, and if the products have less mass than the reactants, it is not that the mass was destroyed.  

- 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