question_answer

An a-particle can be represented by a :

A)  hydrogen atom

B)  helium ion

C)  hydrogen ion   

D)  helium nucleus

Correct Answer: D

Solution :

Alpha particles are composite particles consisting of two protons and two neutrons tightly bound together as shown in figure. They are emitted from the nucleus of some radio nuclides during a form of radioactive decay, called alpha-decay. An alpha, particle is identical to the nucleus of a normal (atomic mass 4) helium atom or a doubly ionized helium atom.