A certain amount of oxygen occupies a volume of 2 m3 at a pressure of 1000 mmHg. What will be the pressure needed to reduce the volume to 0.8 m3 without changing the temperature?

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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.