Almost the entire mass of an atom is concentrated in the ______ .
The mass of the atom is determined by ______ .
The fixed circular paths around the nucleus are called ______ .
The sum of number of protons and neutrons present in the nucleus of an atom is called ______.
An atom is made of all these things except ______.
Which one of the following is the negatively charged particle in an atom ______.
An atom is a neutral particle because ______ .
Which of the following lack neutron?
Which of the following is true for a neutral atom?
Electrons are arranged outside of the atom called ______ .