Answer is: the atom is the smallest known particle of matter.
John Dalton claimed that atom is indestructible and a<span>ll atoms of a given element are identical in mass and properties.
</span>Thomson discovered electron and found the first evidence for isotopes<span> of a stable element.</span>
1 kg/L ----------- 0.001 kg/mL
22.4 kg/L ------- ??
22.4 x 0.001 / 1 => 0.0224 kg/mL
D. all of the above, although I do find it hard to believe something like flour would have a melting point, I looked up my answer to double check.