The answer is The student forgot to add phenolphthalein.
Phenolphthalein<span> is a </span>chemical compound<span> with the </span>formula C20H14O4<span> and is often written as "</span>HIn" or "phph<span>" in shorthand notation. Phenolphthalein is often used as an indicator in </span>acid–base titrations<span>. For this application, it turns colorless in </span>acidic<span> solutions and pink in </span>basic <span>solutions.</span>
A controlled experiment is simply an experiment in which all factors are held constant except for one: the independent variable. A common type of controlled experiment compares a control group against an experimental group. All variables are identical between the two groups except the factor being tested.
hope this helps :)
if not comment and ill give you something different
The inverted cone, hope it helps .
Answer:
The boundary would be a divergent boundary
