Scientists digging in a cave found an unknown substance. The scientists foundthat the substance's molecules were moving around each
other. The scientistsincreased the speed of the substance's molecules
and caused a phase change. How did the scientists do this, and how did
this affect the substance?The scientists transferred energy...

A. into the substance, and the substance changed into a gas.

B. into the substance, and the substance changed into a liquid.

C. out of the substance, and the substance charged into a solid.

D. out of the substance, and the substance changed into a liquid.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

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.