Question Text
Question 2 :
Oxygen consists of isotopes ${{\text{O}}^{16}}\,$,${{\text{O}}^{17}}\,$ and ${{\text{O}}^{18}}\,$ carbon consists of isotopes of ${{\text{C}}^{{\text{12}}}}$ and ${{\text{C}}^{{\text{13}}}}$ Total number of ${\text{C}}{{\text{O}}_2}$ molecules possible are
Question 4 :
Almost the entire mass of an atom is concentrated in the :<br/>
Question 7 :
Which of the following is true for mass and charge of proton?
Question 10 :
It was known by 1900 that the atom was not a............. , ................particle but contained at least one sub-atomic particle the electron identified by J.J. Thomson. 
Question 11 :
Electrons are the kind of particles which revolve around the nucleus.
Question 15 :
___________ said that cathode rays consist of negatively charged particles and these were named as electrons.
Question 16 :
Which of the following is true for mass and charge of electron?
Question 18 :
An atom of silicon has a mass number of $29$. How many neutrons does it have?  
Question 19 :
If an atom contains one electron and one proton, what charge will it carry?
Question 21 :
An atom of an element has 11 protons, 11 electrons, and 12 neutrons. The atomic mass of the atom is:
Question 22 :
Atoms or group of atoms which are electrically charged are known:
Question 24 :
Which of the following contributes the least toward the atomic mass of an element?
