The ion of an element has 3 positive charges. The mass number of atom of this element is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

Goldstein’s experiments which involved passing high voltage electricity through gases at very low pressure resulted in the discovery of:

The number of electrons in the atom of an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of an atom of this element?

The first model of an atom was given by:

Which f the following statement is always correct?