I REALLY NEED help in earth science!!!?

Question

I really need answers to these questions.

A. When an alpha particle is emitted, how do the mass number and the atomic number change, if at all?

2. When three-quater of a radioactive isotope has decayed to become the stable daughter product,---------- half lives have occured.

Answer 1

1. An alpha particle consists of two protons and two neutrons (equivalent to a helium nucleus). A proton has a mass number of +1. A neutron has a mass number of +1. Therefore a nucleus that emits an alpha particle loses 4 mass numbers. A proton has an atomic number of +1. A neutron has an atomic number of 0. Therefore, the nucleus that emits an alpha particle will lose 2 atomic numbers.

After one half-life, half the isotope has decayed. After another half-life, half of the rest has decayed, so in total 3/4 has decayed. After a third half-life, 7/8 has decayed. Etc.