Which equation shows a conservation of mass?

Jose Calaycay: conservation of mass:http://www.youtube.com/user/FatMan27183141

Sibyl Siwik: none of the equations violate conservation of massthe equations are not in balanced form,hence it gives the impression that mass conservation is violated2na + cl2 = 2nacl2al+ 3br2 = 2albr32h2o = 2h2 + o2pcl5 = pcl3 + cl2...Show more

Kalyn Proietto: number 4 does.all the other molecules differ in number of respective atoms, so this is the only one that makes sense.