Html viewer was selected to open .htm files and that would not handle mailto: and other links. This app reset that and then next time I opened the file it asked what app to use and I could select Browser (or Chrome). Perfect. At times, I want to use Chrome to open an .html file that I put on my tablet.
Neutrons have a mass of 1.675 Ã 10-24g, which is a little heavier than the proton. Neutrons are 1839 times heavier than electrons. Like all hadrons, neutrons are made of quarks. A neutron is made of two down quarks and one up quark. One up quark has a charge of +2/3, and the two down quarks each have a charge of -1/3.
So, we ignore the mass of electron and state that the entire atomic mass of an atom resides in its nucleus, which constitutes of protons and neutrons. therefore, mass number= mass of total neutrons present in the atom + mass of total protons present in the atom 125 = x(1) + 50(1) ( as no. of protons= 50) x= 125-50 x=75