Examine the spectra of the four unknown substances shown below. what can you conclude?

substances w and y are the same.
substances x and z are the same.
all of the substances are from the same sample.
none of the substances are the same.

Line spectra are obtained when individual elements are heated using a high-voltage electrical discharge. This heating causes excitation of the element and a subsequent emission of distinct lines of colored light are obtained. Each element has its own unique emission line spectrum; therefore, if any of the tested substances were the same, their spectra would match. However, this is not the case so none of the substances are the same.

The answer is b.the gaseous state is electrically positive, while the plasma state is electrically negative.