Find the number of chromium ions in 3.5 mol of chromium ions.

2.1 x 10^24 Cr ions

Explanation:

You  need to multiply the 3.5 mol by the Avogrado's number (6.022 x 10^23) to get your answer.

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.