Which two objects attract each other?
a.
a proton and an electron
b.
two electrons
c.
a proton and a neutron
d.
two protons

Which changes of state do the labels represent? a: b: c:

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is

If a substance is in the gas phase, which of qualities of the gas will stay constant? a: volume b: mass c: shape d: position of particles