Possibly the third one down. I don't think that DNA was around in Crippen's time. I'm not a criminologist or associated fun and games, though.
Answer:
1.5g/cm³
Explanation:
Given parameters:
Initial volume of the liquid = 30cm³
Final volume of the liquid = 50cm³
Mass of the liquid = 30g
Unknown:
Density of the liquid = ?
Solution:
Density is the mass per unit volume of a substance.
Density = 
volume of the liquid = final volume - initial volume = 50cm³ - 30cm³
volume of the liquid = 20cm³
Density = 
= 1.5g/cm³
FULL ANSWER
Neutrons and protons make up a nucleus and they are in the middle of an atom. Electrons surround the nucleus. Opposite charges attract each other. Because of this, protons do not attract other protons and electrons do not attract other electrons. Instead, protons attract electrons and electrons attract protons. When someone looks at the elements on the periodic table, they can see how many protons are present by looking at the atomic number. Since atoms have to have an equal amount of each, if an element contains 36 protons, it also has 36 electrons.
I would say that it is Meteors, Meteorites, and comets. (METEORS may be wrong)
