2. Which of these has a negligible mass?
Protons Neutrons Electrons Atoms None of these
3. Which of these is a pure substance?
Blood Ocean Brass Wine Table Salt (NaCl)
4. Which of these is not an element?
Uranium Plutonium Iron Gold Brass
5. Which of these has 23 protons?
Scandium Titanium Vanadium Chromium None of these
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