Select the correct answer from each drop-down menu. Complete these descriptions of different kinds of chemical reactions.

A
reaction involves burning. This reaction requires energy to start, but it releases more energy than is required to start it. Oxygen is always a reactant, and the products are usually carbon dioxide and water.

A
reaction occurs when a compound breaks down. This reaction has one reactant and two or more products. Energy, as from a battery, is usually needed to break the compound apart.

A ___
reaction occurs when two substances combine to form one substance. An example of this kind of reaction is rusting, in which iron reacts with oxygen.

A reaction that involves the replacement of atoms is a
reaction. An atom from one reactant replaces an atom in the other reactant. This kind of reaction has two reactants and two products. An example is the neutralization of an acid and an alkali.

- 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

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

c) should be the answer.

the answer is yes

it has kinetic energy

reason

an object has kinetic energy when you stop the force carrying it, the object will stay in motion.

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