Section 20.1 the meaning of oxidation and reduction answer key

Oxidation is defined as the reaction in which there is loss of electrons. It  is accompanied by increase in oxidation number.

Fe being the pure element in its standard state has oxidation number of zero and on loosing electron changes to oxidation number of +2.

Reduction is defined as the reaction in which there is gain of electrons. It  is accompanied by decrease in oxidation number.

Iron changes from oxidation number of +2 to pure iron [Fe} with oxidation number of zero.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.