Is FeS + HNO3 ⟶ Fe(NO3)2 + H2S a redox reaction?

pure substance: iron,copper

impure substance: water,charcoal

58750.08068 is the answer i think

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.

i think it's letter a.