That statement is true
it was easy to organize 'all' the elements in a group of threes because back then they only knew about 15 - 20 elements
hope this helps
Base pairs are more biology but they are what make up DNA there are 4 (adenine, thymine, guanine, and cytosine) they each pair with each other (A to T and G to C).
Yes it is a exothermic reaction.
<span> Substance 1 was activated by the heat and inactivated by ice, Substance 2 was activated by the change in concentration, and Substance 3 increased the surface area.</span>