Alex has a type of rock called calcite, that sometimes glows. He puts the calcite under a desk lamp but the calcite does not glow. Then he puts it under an ultraviolet lamp and the calcite glows. Why does ultraviolet light make the calcite glow when light from the desk lamp does not? *
1 point

6.4 cm (max) - 25 cm (min)

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.