Which of the following are True for α α -decay. i. mass number, decrease by four. ii. Atomic number decreases by two. iii. mass number does not change.

Answer Details

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle consisting of two protons and two neutrons, reducing its atomic number by two and its mass number by four. Therefore, statement i is correct. The atomic number is the number of protons in the nucleus, and in alpha decay, two protons are lost. Hence, statement ii is also correct. However, the number of neutrons in the nucleus remains the same in alpha decay, so statement iii is incorrect. Therefore, the correct option is "i and ii only."