Select the correct answer.
why does every chemical reaction require a certain amount of activation energy?
o a
energy is released when the reactants begin to react.
o b. energy lost to the environment during the reaction must be replaced.
oc forming the activated complex requires energy.
od. the products have more potential energy than the activated complex.
o e.
the reactants have less potential energy than the products.

The first one

Explanation:

Out of those I'd say the first ones the most right, chemical bonds have to be broken to start a chemical reaction which is exothermic and does release energy.

So yea the top one I reckon.

- 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