Question

Which of the following is not emitted by radioactive substances?

• A. Electrons (beta particles)
• B. Electromagnetic radiations (gamma rays)
• C. Alpha particles
• D. Neutrons

Hint:

Recall the three basic types of radioactive decay: alpha, beta and gamma.

Answer 1

The Correct Option is D

Step 1: List the decay types.
A radioactive nucleus can break down in three standard ways, alpha decay, beta decay, and gamma decay.
Step 2: Match each type to what it emits.
Alpha decay releases an alpha particle, which is a helium nucleus with two protons and two neutrons. Beta decay releases a fast electron, called a beta particle, formed when a neutron inside the nucleus turns into a proton. Gamma decay releases gamma rays, which are high energy electromagnetic radiation, not a particle of matter.
Step 3: Check the fourth option.
A free neutron is not part of any of these three standard decay processes. Neutrons are released only in special events like nuclear fission, which is a different phenomenon from ordinary natural radioactivity.
Step 4: Confirm the odd one out.
Since alpha particles, beta particles and gamma rays are all genuine products of radioactive decay, and neutrons are not, neutrons are the answer.
Final Answer: D) Neutrons.