Activity A: Alpha Decay Get the Gizmo ready:
Click Reset ().
Check that Alpha decay and Uranium are selected.
Question: How does alpha decay change the nucleus of a radioactive atom?

Predict: As you observed in the warm-up activity, an alpha particle consists of two protons and two neutrons. How will the emission of an alpha particle affect the following?

Calculate: Turn on Write equation. What you see is an equation that shows the original uranium atom on the left. The boxes on the right represent the daughter product—the atom produced by radioactive decay—and the emitted alpha particle.

In the top left box, write the mass number of the daughter product and press “Enter” on your keyboard. What is this number?
Please Help me, I really need to ace this answer.