What is the oxidation state of Sin SO 3 ^ 2- ?

Oxidation state of S in SO3^2- is +4

Explanation:

S in SO3^2-=

S = ?

O = -2

S + 3 moles of O * -2 = -2

S + (-6) = -2( it has charge -2)

S - 6 = -2

S = -2 + 6

S = +4

Note, the sign is very important

Don't confuse SO3 together with SO3^2-, the oxidation state of S in SO3 is + 6, how?

S = ?

O = -2

S + 3 * -2 = 0 ( because it has no charge)

S - 6 = 0

S = +6

And in SO3^2-

S = +4

The difference is that one has charge SO3^2- and the other doesn't SO3.

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.