11.In beta decay

12.(4n + 1) radioactive disintegration series is also known as

13.After one hour, 1/8 of the initial mass of a certain radioactive substance remains undecayed. The half-life of the isotope is

14.As a result of a number of successive decay processes in a radioactive series the nucleon number decreases by 4 while the proton number is unchanged. The particles emitted are

15.Which of the following particles is considered to be responsible for keeping nucleons together?