Which one of the following statements is true?

The speed of radioactive decay cannot be regulated, whereas nuclear fission can be regulated
Nuclear forces act over very small distances, are attractive in nature, and depend on charge
Atoms with the same number of neutrons are called isobars
The wavelength of matter waves is given by the de Broglie relation, but photons do not follow the same relation

Correct answer: The speed of radioactive decay cannot be regulated, whereas nuclear fission can be regulated

Solution

Radioactive decay is spontaneous with a fixed rate that cannot be controlled, whereas nuclear fission (a chain reaction) can be regulated, e.g. with control rods. The other options are false: nuclear forces are charge-independent, equal-neutron nuclei are isotones (not isobars), and photons also obey lambda = h/p.

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