<span>The independent variable is the one that does not change depending on other variables - so here it would be the presence or the absence of caffeine - this is dependent on Tina's actions, but not on other variables in the experiment. The dependent variable is the heart rate - it is assumed to depend on the presence or absence of caffeine. A hypothesis could be that "Caffeine causes an increase of heart rate in earthworms" - and this hypothesis is what the experiment is testing.</span>
Br + Br -> Br2 (covalent bond)
<span>forming of bonds releases energy, since the Br's are at a lower energy state as Br2
Answer is #3</span>
This is a simple chemical change due to what it produces and how it is added together. Hope this helps.
Answer:
minerals are inorganic solids.
Explanation:
they have a definite chemical composition, its a solid chemical compound that occurs naturally in pure form. minerald are most commonly associated with rocks.
