Some farmers leave a strip of land around the edge of each field which they do
not spray with chemicals.

Suggest two reasons why this will lead to an increase in the number of partridges
on these farms.

i'm wiling to try and you : )

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.