In the chemical formula CO2, the subscript 2 shows which of the following?
a) there are two oxygen ions
b) there are two oxygen atoms
c) there are two carbon atoms
d) there are two CO2 molecules
The atomic number of fluorine (F) is 9. Its mass number is 19. How many neutrons are present in its atom?
a) 7
b) 8
c) 9
d) 10
For the first time the idea of an atom was given by Democritus:
a) Latin philosopher
b) Greek philosopher
c) Russian philosopher
d) none of these
………..John Dalton from England presented the first atomic model.
a) 17th Century
b) 18th Century
c) 19th Century
d) 20th Century
According to John Dalton which of the following can neither be created nor destroyed?
a) atom
b) electron
c) proton
d) none of these
Which of the following revolves around the nucleus?
a) atom
b) electron
c) proton
d) neutron
