Place the following in size order with the smallest first.
Proton
Molecule
Cell
Atom
Quark
Photon
Lepton
Electron

Hi!!

-Photon : a quantum of electromagnetic radiation, it has no mass.

-Electron (smaller lepton with mass)

-Lepton (average): any of a group of elementary particles and their
antiparticles, such as an electron, tau, muon, or neutrino.
http://www.wordiq.com/cgi-bin/knowledge/lookup.cgi?title=Lepton

-Quark: In particle physics, the quarks are one of the two families of
subatomic particles thought to be elemental and indivisible (the other
being the leptons). Objects made up of quarks are known as hadrons;
well known examples are protons and neutrons.
http://www.wordiq.com/cgi-bin/knowledge/lookup.cgi?title=Quark

-Atom

-Molecule: the simplest unit of a chemical compound that can exist,
consisting of two or more atoms held together by chemical bonds.

-Cell

Hope this helps. Feel free to request for a clarification if it needed.