What is the order of decreasing reactivity of these 4 metals?

Ca, Mg, Zn, Cu

Explanation:

Refer to the Reactivity Series where each metal is more reactive than others.

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.

answer///carbon;