Question

$\alpha -rays$ are composed of:

• A. fast moving protons
• B. fast moving electrons
• C. the same particles that constitute positive rays
• D. particles with four mass units and two positive charges

Answer 1

The correct option is D particles with four mass units and two positive charges

$\alpha$- rays consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. They are generally produced in the process of alpha decay, but may also be produced in other ways.

So, answer is D.