atomic numbeer

which of the following particles is positively charged in atom ?

• protons

• neutrons

• electrons

• both(a) and (b)

what is the number of protons is an element with atomic number 17 and mass number 37?

• 17

• 20

• 22

• 21

elements having the same atomic number but different mass number are called ?

• isotones

• isotopes

• isobers

• none of the above

the number of electrons in a neutral atoms represents its ?

• atomic number

• atomic mass

• mass number

• number of nucleons

which of the following contribute mainly to the mass of an atom ?

• neutrons and electron

• proton and electron

• neutron and proton

• none of the above