1u is defined as per carbon 12 so 1 atom of c have 6 neutrons and 6 protons both having mass more than 1u (Google)so total mass of carbon 12 is more then 12u (also there would be some mass of electrons) but it should be exactly 12u as u is defined such.So what should i interpret.I am confused how this is possible
I am just a school student just entered chemistry