Question

Define mass number and atomic number. How are there represented around the symbol of an element? The mass number and atomic number o an isotope of uranium (U) are 235 and 92 respectively

Answer 1

 Mass number of an element is the total number of protons and neutrons present in the nucleus of anatom. For example, Mass Number of Carbon: There are present 6 protons and 6 neutrons in the nucleus of carbon atom, so mass number of carbon element is 12.