Decay Rate

Neutrons and protons are nucleons, but neutrons are not composed of a proton and an electron. Neutrons have no net electric charge, so the electric force has a weaker effect on them.

• Free neutrons are unstable and undergo beta decay, with a mean lifetime of around 15 minutes.
• This decay is possible because the neutron's mass is slightly greater than that of a proton.
• In contrast, free protons are stable and do not decay into neutrons.
• Neutron decay involves the conversion of a neutron into a proton, an electron, and an electron antineutrino.

The correct answer is (b) a neutron has a larger rest mass than a proton.

Discover More From Chapter: Nuclei

Step 1: Calculate the Number of Moles

The number of moles is given by:

Substitute the given values:

Step 2: Calculate the Number of Atoms

Using Avogadro’s number ( ):

Simplify:

Step 3: Calculate the Initial Activity ( )

The activity at is given by:

Substitute and :

Simplify:

Final Answer:

The initial activity is