A hot, low density gas like that left behind after a supernova will have... Group of answer choicesa purely continuous spectrumsocksstrong emission lines corresponding to isotopes withindark absorption lines within their spectra

The correct answer is: strong emission lines corresponding to isotopes within.

Here's why:

1. A supernova is a powerful explosion that occurs when a star has used up its nuclear fuel. This explosion releases a lot of energy and ejects the outer layers of the star into space.

2. The gas left behind after a supernova is hot and low density. This gas is composed of various elements, including isotopes, which are variants of a particular chemical element that differ in neutron number.

3. When this gas is heated, the atoms within it become excited and their electrons move to higher energy levels. When the electrons drop back down to their original energy levels, they emit light.

4. The light emitted by these atoms produces emission lines in the spectrum. These lines correspond to the specific energies of the photons emitted, which in turn correspond to the specific isotopes within the gas.

5. Therefore, a hot, low density gas like that left behind after a supernova will have strong emission lines corresponding to isotopes within.

The other options are incorrect because a hot, low density gas like that left behind after a supernova will not have a purely continuous spectrum or dark absorption lines within their spectra. The "socks" option is not related to the topic at all.