The atoms of the same element, having the same atomic number Z but different mass number A are called :

1. Isotopes
2. Isobars
3. Isotones
4. None of the above

Out of the following, which element has the largest number of isotopes ?

1. Hydrogen
2. Carbon
3. Chlorine
4. Tin

Out of the following, radioactive substances are :

1. Uranium
2. Polonium
3. Actinium
4. All of the above

The heaviest nuclear radiation is :

1. X radiation
2. α radiation
3. γ radiation
4. β radiation