Ascientist is performing an experiment on a powder. which of the following is a sign that a chemical change has definitely occurred during his experiment?
the powder catches on fire
the powder bubbles
the power heats up
the powder brakes into small particles

"do a testcross with a homozygous recessive plant."

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

they dont have any evidence

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.