Atomic Structure and Atomic Mass

Which of the following is not a particle of atom?

• Proton

• Electron

• Positron

• Neutron

The nucleus of an atom has

• Proton and electron

• Proton and neutron

• Electron and neutron

• Proton only

Atomic number is the number of

• Protons

• Electrons

• Neutrons

Mass number is the total number of

• Protons, electrons and neutrons

• Protons and electrons

• Protons and neutrons

• Electrons and neutrons

The mass number of an element is 31 and the atomic number is 15. How many electrons does it have?

• 14

• 15

• 16

• 31

The mass number of an element is 31 and the atomic number is 15. How many neutrons does it have?

• 15

• 14

• 16

• 31

An element has 19 electrons and 20 neutrons. What is its atomic number?

• 39

• 19

• 20

• 1

Isotopes have same atomic number but different

• number of protons

• number of electrons

• number of neutrons

Spontaneous emission of radiation when an isotope becomes unstable is called

• Radioactivity

• Diffusion

• Reflection

• Magnetism

Relative abundance of an isotope is the percentage of that isotope in the naturally occurring environment

• True

• False