A nucleus with mass number 240 breaks into two fragments each of mass number 120, the binding per nucleon of unfragmented nuclei is 7.6MeV while that of fragments is 8.5MeV. The total gain in the Binding Energy in the process is :

The half life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be :

A radioactive nucleus
$$_Z^AX$$ $$\to$$ $${}_{Z - 1}B$$ $$\to$$ $${}_{Z - 3}C$$ $$\to$$ $${}_{Z - 2}D$$,
where Z is the atomic number of element X. The possible decay particles in the sequence are :