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Question Video: Describing an Object That Has Been Radioactively Contaminated Science

Which of the following correctly describes whether or not an object is radioactively contaminated? [A] An object is radioactively contaminated if it has absorbed nuclear radiation. [B] An object is radioactively contaminated if radioactive material has become joined to it.

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Video Transcript

Which of the following correctly describes whether or not an object is radioactively contaminated? (A) An object is radioactively contaminated if it has absorbed nuclear radiation. (B) An object is radioactively contaminated if radioactive material has become joined to it.

This question is asking what must happen to an object for it to be considered to be radioactively contaminated. To answer this question, we must understand what “radioactively contaminated” means.

Contamination is a type of mixing process. A contaminant is something that can become mixed into uncontaminated objects. The question asks specifically about radioactive contamination. It is helpful then to recall what “radioactive” means.

A substance is radioactive if it contains atoms that can emit nuclear radiation. The meaning of radioactive contamination is still not exactly clear however. Radioactive contamination could mean contamination of an object that is caused by radioactive material. Radioactive contamination could also mean contamination of an object with some radioactive material. A helpful way to further understand what contaminated means is to understand that an object that is contaminated may go on to contaminate other objects.

Remembering what we have just been told about contamination and radioactivity, let us consider the options in the question. The options are that an object absorbs nuclear radiation or that an object has had radioactive material join to it. Let us consider what the difference between these two options is.

If an object absorbs nuclear radiation, this means that nuclear radiation has entered the object. If an object has had radioactive material joined to it, this means that radioactive atoms have entered the object.

Recall that an object that is contaminated may go on to contaminate other objects. So, if radioactive contamination means that an object absorbs nuclear radiation, we could describe the process of contamination as follows. An object absorbs nuclear radiation and becomes contaminated. Then, the contaminated object emits nuclear radiation that can contaminate other objects.

Let us consider an object that is initially not radioactive, such as water in a container. This water cannot emit nuclear radiation as it is not radioactive. This water now absorbs some nuclear radiation from a radioactive rock that is held over the surface of the water. The rock is then taken away. Is the water now radioactive? No, the water will not emit nuclear radiation. Absorbing nuclear radiation does not make stable atoms in the water become unstable atoms.

Now, instead, let’s consider what would happen if you poured some radioactive fluid into a container of pure water. Since both are fluids, we would expect them to mix together in the container. After the fluids have mixed in the container, it is correct to say that unstable atoms from the radioactive fluid have transferred to the container of water and the water is now a source of nuclear radiation. Therefore, it is correct to say that an object, such as the water in our example, is radioactively contaminated when radioactive material has become joined to it or become a part of it.

Now, we can identify option (B) as the correct answer. An object is radioactively contaminated if radioactive material has become joined to it.

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