Question

which of the following best describes radioactivity?
select one:
a. the amount of reactants converted to products in a certain amount of time.
b. the nuclear force that holds the protons and neutrons in the nucleus.
c. the spontaneous release of nuclear particles and energy.
d. the penetrating ability of nuclear particles.

which of the following statements is true of stable isotopes?
select one:
a. they naturally decay into new elements.
b. they have half - lives.
c. they spontaneously release nuclear particles and energy.
d. they cannot be detected with a radioactive detector.

Explanation:

For the first question:

• Option a describes reaction rate, not radioactivity.
• Option b describes the strong nuclear force, not radioactivity.
• Option c matches the core definition of radioactivity: unstable nuclei spontaneously emit particles/energy.
• Option d describes a property of radioactive emissions, not radioactivity itself.

For the second question:

• Option a, b, c describe properties of radioactive (unstable) isotopes, not stable ones.
• Stable isotopes do not undergo radioactive decay, so they cannot be detected by a radioactive detector which senses decay emissions.

Answer:

1. c. The spontaneous release of nuclear particles and energy.
2. d. They cannot be detected with a radioactive detector.