Select all that apply.
1: which of the following particles are of approximately equal mass?
a: protons
b: electrons
c: neutrons
d: quarks

2: if the atomic number of an element is 16, then it has 16 electrons.
true
false

3: an unknown substance is tested and found to have the following physical properties:
brittle
fair conductor of electricity
dull (not shiny)
the substance is most likely a
a: metal
b: metalloid
c: nonmetal
d: can not be determined without more data