What is the number of electronsin hydrogen

What term describes technology that operates on an atomic level

If e is the symbol for an element, which two of the following symbols represent isotopes of the same element? 1. e2. e3. ea.1 and 2c.1 and 4b.3 and 4d.2 and 3

Robert leaves a chocolate bar in his car while attending school all day. when he goes to his car in the afternoon, the bat has changed into gooey liquid. what happened to the chocolate bar